Fluid-assisted medical devices, systems and methods

ABSTRACT

A medical device is provided which comprises a catheter tube having a distal end and a lumen, and configured to assist in applying tamponage to a bleeding source in a gastrointestinal tract when flexed. A catheter tip having a catheter tip outer surface is assembled with the tube adjacent the distal end of the tube. The catheter tip comprises a probe body comprising an electrically insulative material, at least one electrode pair located on the probe body which comprises a first electrode spaced from a second electrode, and a fluid distribution manifold to direct a fluid from inside the probe body towards the tip outer surface. The manifold comprises a central passage within the probe body and a plurality of lateral passages which extend from the central passage towards the tip outer surface. An extendable injection needle is housed within the central passage to provide treatment to tissue.

This application is a continuation of U.S. patent application Ser. No.10/494,597 filed May 4, 2004, now U.S. Pat. No. 7,311,708, which is a371 application of PCT application PCT/US02/39701, filed Dec. 11, 2002which claims priority to U.S. Provisional application No. 60/340,429,filed Dec. 12, 2001, the entire disclosures of which are incorporatedherein by reference.

FIELD OF THE INVENTION

This invention relates generally to the field of medical devices,methods and systems for use upon a body during surgery. Moreparticularly, the invention relates to electrosurgical devices, methodsand systems for use upon tissues of a human body during therapeuticendoscopy.

BACKGROUND

Electrosurgical devices configured for use with a dry tip use electricalenergy, most commonly radio frequency (RF) energy, to cut tissue or tocauterize blood vessels. During use, a voltage gradient is created atthe tip of the device, thereby inducing current flow and related heatgeneration in the tissue. With sufficiently high levels of electricalenergy, the heat generated is sufficient to cut the tissue and,advantageously, to stop the bleeding from severed blood vessels.

Current dry tip electrosurgical devices can cause the temperature oftissue being treated to rise significantly higher than 100° C.,resulting in tissue desiccation, tissue sticking to the electrodes,tissue perforation, char formation and smoke generation. Peak tissuetemperatures as a result of RF treatment of target tissue can be as highas 320° C., and such high temperatures can be transmitted to adjacenttissue via thermal diffusion. Undesirable results of such transmissionto adjacent tissue include unintended thermal damage to the tissue.

Using saline to couple RF electrical energy to tissue inhibits suchundesirable effects as sticking, desiccation, smoke production and charformation. One key factor is inhibiting tissue desiccation, which occursif tissue temperature exceeds 100° C. and all of the intracellular waterboils away, leaving the tissue extremely dry and much less electricallyconductive. However, an uncontrolled or abundant flow rate of saline canprovide too much cooling at the electrode/tissue interface. This coolingreduces the temperature of the target tissue being treated, and the rateat which tissue thermal coagulation occurs is determined by tissuetemperature. This, in turn, can result in longer treatment time toachieve the desired tissue temperature for treatment of the tissue. Longtreatment times are undesirable for surgeons since it is in the bestinterest of the patient, physician and hospital to perform surgicalprocedures as quickly as possible.

RF energy delivered to tissue can be unpredictable and often not optimalwhen using general-purpose generators. Most general-purpose RFgenerators have modes for different waveforms (e.g. cut, coagulation, ora blend of these two) and device types (e.g. monopolar, bipolar), aswell as power levels that can be set in watts. However, once thesesettings are chosen, the actual power delivered to tissue and associatedheat generated can vary dramatically over time as tissue impedancechanges over the course of RF treatment. This is because the powerdelivered by most generators is a function of tissue impedance, with thepower ramping down as impedance either decreases toward zero orincreases significantly to several thousand ohms. Current dry tipelectrosurgical devices are not configured to address a change in powerprovided by the generator as tissue impedance changes or the associatedeffect on tissue and rely on the surgeon's expertise to overcome thislimitation.

One medical condition which employs RF energy in treatment isgastrointestinal (GI) bleeding, with such treatment typicallyadministered via gastrointestinal endoscopy. Bleeding in the uppergastrointestinal tract may result from, for example, peptic ulcers,gastritis, gastric cancer, vascular malformations such as varices (e.g.esophageal) and other lesions. Bleeding in the lower gastrointestinaltract may result from, for example, vascular malformations such ashemorroidal varices.

Peptic ulcer bleeding is one of the most common types of non-varicealupper gastrointestinal bleeding. Peptic ulcer bleeding results from thecombined action of pepsin and hydrochloric acid in the gastric ordigestive juices of the stomach. Peptic ulcers further include, forexample, gastric ulcers, an eroded area in the lining (gastric mucosa)of the stomach, and duodenal ulcers, an eroded area in the lining(duodenal mucosa) of the duodenum. Peptic ulcers may also be found inMeckel's diverticulum.

Endoscopic modalities for the treatment of upper gastrointestinalbleeding include injection therapy (e.g. diluted epinephrine,sclerosants, thrombogenic substances, fibrin sealant), mechanical clipsand so called thermal (heating) methods. Thermal methods are oftendivided into so called non-contact thermal methods and contact thermalmethods. Non-contact thermal methods include laser treatment and, morerecently, argon plasma coagulation (APC). Thermal contact methodsinclude multipolar electrocoagulation and thermal coagulation probes.

Non-contact thermal probe methods depend on the heating of tissueprotein, contraction of the arterial wall and vessel shrinkage. Onedrawback of non-contact thermal methods is the “heat sink effect” whereflowing arterial blood leads to dissipation of the thermal energy.Because of the greater tissue penetration, the neodymium: yttriumaluminum garnet (Nd:YAG) laser is generally superior to the argon laserfor ulcer hemostasis. In any event, laser units are expensive, bulky andgenerally not portable. They are also difficult to use as an en faceview of the bleeding ulcer is often required. For these reasons, laserphotocoagulation has generally fallen out of favor for the treatment ofulcer bleeding. The argon plasma coagulator uses a flowing stream ofargon gas as the conductor for electrocoagulation. This method isgenerally effective for mucosal bleeding but may not be effective incoagulating an eroded artery in a bleeding ulcer. Also, as flowing gasis required, care must be taken to avoid overdistention of the stomachduring treatment.

Contact thermal probes utilize the principle of “coaptive coagulation”.First, mechanical pressure is applied to the bleeding vessel to compressthe vessel before heat or electrical energy is applied to seal thebleeding vessel. Compression of the blood vessel also reduces the bloodflow and reduces the heat sink effect. Multiple pulses of energy aregiven to coagulate the bleeding vessel to achieve hemostasis. Thesemethods are effective in hemostasis but carry a potential risk ofinducing bleeding when an adherent probe is pulled off a bleedingvessel. Furthermore, contact devices require accurate targeting of thebleeding vessel for successful ulcer hemostasis.

Multipolar electrocoagulation devices include the BICAP® HemostasisProbe from ACMI Circon (300 Stillwater Avenue, Stamford, Conn. 06902)and the Gold Probe™ from Microvasive (480 Pleasant Street, Watertown,Mass. 02172). A third multipolar electrocoagulation device is theInjector-Gold Probe™, also from Microvasive, which incorporates aninjection needle for use with epinephrine.

According to Dr. Joseph Leung's publication entitled “EndoscopicManagement of Peptic Ulcer Bleeding”, an “ideal” endoscopic hemostaticdevice should have the following properties. It should be effective inhemostasis, safe, inexpensive, easy to apply and portable. Thus, costand non-portability issues associated with laser therapy have generallymade it a less favorable treatment for ulcer hemostasis. Consequently,electrocoagulation or thermal coagulation have largely replaced lasertherapy as a more routine treatment. Injection therapy generally has anadvantage over the above contact thermal devices in that the injectiondoes not need to be very accurate and can be performed through a pool ofblood, but the cost of the medication is a disadvantage.

Turning to the argon plasma coagulator, according to in the publication“A Randomized Prospective Study of Endoscopic Hemostasis with ArgonPlasma Coagulator (APC) Compared to Gold Probe™ (GP) for Bleeding GIAngiomas”, Jutabha and colleagues compared the efficacy and safety ofAPC and GP for hemostasis of bleeding GI angiomas and describe theadvantages and disadvantages of each type of treatment for angiomapatients. Thirty-four patients with angiomas as the cause of acute orchronic GI bleeding, not responsive to iron supplementation alone, werestratified by syndrome (i.e., UGI, LGI angiomas; watermelon stomach;jejunal angiomas; radiation telangiectasia) and randomized to treatmentin a prospective study: 16 to APC and 18 to GP.

According to the publication, there were 2 major complications of APC.While there were no significant differences between most clinicaloutcomes of APC versus GP patients, investigators observed that APC wassignificantly slower than GP and more difficult to use because ofseveral features of APC: it could not coagulate through blood or water,smoke was common which interfered with visualization and increased gutmotility, tamponade of bleeders was not possible, and tangentialcoagulation was difficult or often blind.

The differences between APC and GP were more marked with multipleangioma syndromes. Although APC is a “no touch technique,” the catheterwas difficult to hold 2-3 mm off the mucosa, which affords the bestcoagulation of a dry field. These features resulted in 6 failures andcrossovers with APC and none with GP. There were no major disadvantagesof GP except that coagulum needed to be cleaned off the tip aftertreatment of multiple angiomas. The authors concluded that forhemostasis of bleeding angiomas, both the APC and GP were effective, butthere were substantial problems with the newer APC device, and overallthe GP performed better.

In light of the above, what is needed is a endoscopic hemostatic devicewhich offers advantages of both the so called non-contact and contactdevices and methods without associated disadvantages. Thus, for example,what is needed is an endoscopic hemostatic device which is preferablyportable and inexpensive. Furthermore, preferably the device should becapable of tissue contact and tamponage associated with coaptivecoagulation to reduce the heat sink effect and facilitate treatment ofan eroded artery, but be less likely to induce bleeding when the deviceis removed from a treated vessel. Furthermore, preferably the deviceshould be capable of coagulation through blood or water (i.e. withoutcontact) as well as tangential coagulation, without generating smokewhich raises possible problems of visualization, gut motility or stomachoverdistenation. Furthermore, preferably the device should be capable ofgenerating tissue hemostasis at a temperature high enough to result intissue shrinkage, but at a temperature low enough not to necessarilycreate char (e.g. dried blood) formation or produce scabs, which maybesubsequently dissolved by digestive juices a result in rebleeding.Furthermore, preferably the device should be capable of use on anysurface of the GI tract without regard for orientation. In other words,for example, preferably the device may be used to treat any surface ofthe stomach, whether above, below or to the side.

SUMMARY OF THE INVENTION

According to one aspect of the invention, an electrosurgical device andmethods for use are provided which comprises an electrosurgical deviceouter surface and includes a probe body, at least one conductor paircomprising a first electrode separated by a gap from a second electrode,and means in fluid communication with the lumen of a tube fordistributing a fluid provided from the lumen of the tube to at least aportion of the surface of the electrosurgical device.

Also according to the invention, a catheter assembly is provided whichcomprises a catheter having a distal end and a lumen, and anelectrosurgical device assembled with the catheter adjacent the distalend thereof. The electrosurgical device comprises an electrosurgicaldevice outer surface and includes a probe body, at least one conductorpair comprising a first electrode separated by a gap from a secondelectrode, and means in fluid communication with the lumen of thecatheter for distributing a fluid provided from the lumen of thecatheter to at least a portion of the surface of the electrosurgicaldevice.

According to another embodiment of the invention, a catheter assembly isprovided which comprises a catheter having a distal end and a lumen, andan electrosurgical device assembled with the catheter adjacent thedistal end thereof. The electrosurgical device comprises anelectrosurgical device outer surface and includes a probe body, at leastone conductor pair comprising a first electrode separated by a gap froma second electrode, and a fluid flow manifold located within the probebody. The fluid flow manifold includes at least one flow passageextending longitudinally within the probe body and at least one flowpassage lateral to the longitudinal flow passage. The longitudinal flowpassage comprises a longitudinal flow passage fluid entrance opening influid communication with the lumen of the catheter and is at leastpartially defined distally by an occlusion. The lateral flow passage isin fluid communication with the longitudinal flow passage and extendsthrough the probe body from the longitudinal flow passage towards theelectrosurgical device outer surface.

According to another embodiment of the invention, a catheter assembly isprovided which comprises a catheter, the catheter having a distal endand a lumen, and an electrosurgical device assembled with the catheteradjacent the distal end thereof. The electrosurgical device comprises anelectrosurgical device outer surface and includes a probe body, at leastone conductor pair, the conductor pair comprising a first electrodeseparated by a gap from a second electrode, and means in fluidcommunication with the lumen of the catheter for distributing a fluidprovided from the lumen of the catheter to at least a portion of thesurface of the electrosurgical device.

According to another embodiment of the invention, a medical device isprovided which comprises a catheter tube having a distal end and alumen, and configured to assist in applying tamponage to a bleedingsource in a gastrointestinal tract when flexed. A catheter tip having acatheter tip outer surface is assembled with the tube adjacent thedistal end of the tube. The catheter tip comprises a probe bodycomprising an electrically insulative material, at least one electrodepair located on the probe body which comprises a first electrode spacedfrom a second electrode, and a fluid distribution manifold to direct afluid from inside the probe body towards the tip outer surface. Themanifold comprises a central passage within the probe body and aplurality of lateral passages which extend from the central passagetowards the tip outer surface. An extendable injection needle is housedwithin the central passage to provide treatment to tissue.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing one embodiment of a control system ofthe invention, and an electrosurgical device;

FIG. 2 is a schematic graph that describes the relationship between RFpower to tissue (P), flow rate of saline (Q), and tissue temperature (T)when heat conduction to adjacent tissue is considered;

FIG. 2A is a schematic graph that describes the relationship between RFpower to tissue (P), flow rate of saline (Q), and tissue temperature (T)when the heat required to warm the tissue to the peak temperature (T) 68is considered;

FIG. 3 is schematic graph that describes the relationship between RFpower to tissue (P), flow rate of saline (Q), and tissue temperature (T)when heat conduction to adjacent tissue is neglected;

FIG. 4 is a graph showing the relationship of percentage saline boilingand saline flow rate (cc/min) for an exemplary RF generator output of 75watts;

FIG. 5 is a schematic graph that describes the relationship of loadimpedance (Z, in ohms) and generator output power (P, in watts), for anexemplary generator output of 75 watts in a bipolar mode;

FIG. 6 is a schematic graph that describes the relationship of time (t,in seconds) and tissue impedance (Z, in ohms) after RF activation;

FIG. 7 is a schematic perspective view of a viewing scope with anelectrosurgical device according to one embodiment of the invention;

FIG. 8 is a schematic close-up view of the distal end portion of theviewing scope of FIG. 7 bounded by circle A with an electrosurgicaldevice according to one embodiment of the invention;

FIG. 9 is a schematic close-up front perspective view of anelectrosurgical device according to one embodiment of the invention;

FIG. 10 is a schematic partially exploded close-up rear perspective viewof the electrosurgical device of FIG. 9;

FIG. 11 is a schematic close-up side view of the electrosurgical deviceof FIG. 9 as part of a medical device assembly;

FIG. 12 is a schematic close-up cross-sectional view of the assembly ofFIG. 11 taken in accordance with line 12-12 of FIG. 13;

FIG. 13 is a schematic close-up front view of the electrosurgical deviceof FIG. 9;

FIG. 14 is a schematic close-up rear view of the electrosurgical deviceof FIG. 9 with member 51 removed;

FIG. 15 is a schematic close-up cross-sectional view of theelectrosurgical device of FIG. 9 taken in accordance with line 15-15 ofFIG. 12;

FIG. 16 is a schematic close-up cross-sectional view of theelectrosurgical device of FIG. 9 taken in accordance with line 16-16 ofFIG. 12;

FIG. 17 is a schematic close-up front perspective view of anelectrosurgical device according to another embodiment of the invention;

FIG. 18 is a schematic close-up cross-sectional view of the assembly ofthe electrosurgical device of FIG. 17 and tube 19 taken in accordancewith line 12-12 of FIG. 13;

FIG. 19 is a schematic close-up cross-sectional view of theelectrosurgical device of FIG. 17 taken in accordance with line 19-19 ofFIG. 18;

FIG. 20 is a schematic close-up front perspective view of anelectrosurgical device according to another embodiment of the invention;

FIG. 21 is a schematic close-up cross-sectional view of the assembly ofthe electrosurgical device of FIG. 20 and tube 19 taken in accordancewith line 12-12 of FIG. 13;

FIG. 22 is a schematic close-up cross-sectional view of theelectrosurgical device of FIG. 20 taken in accordance with line 22-22 ofFIG. 21;

FIG. 23 is a schematic close-up partial cross-sectional view of anelectrosurgical device according to another embodiment of the inventiontaken in accordance with line 22-22 of FIG. 21;

FIG. 24 is a schematic close-up cross-sectional view of the assembly ofan electrosurgical device according to another embodiment of theinvention and tube 19 taken in accordance with line 12-12 of FIG. 13;

FIG. 25 is a schematic close-up partial cross-sectional view of anelectrosurgical device according to another embodiment of the inventiontaken in accordance with line 22-22 of FIG. 21;

FIG. 26 is a schematic close-up partial cross-sectional view of anelectrosurgical device according to another embodiment of the inventiontaken in accordance with line 22-22 of FIG. 21;

FIG. 27 is a schematic close-up partial cross-sectional view of anelectrosurgical device according to another embodiment of the inventiontaken in accordance with line 22-22 of FIG. 21;

FIG. 28 is a schematic close-up partial cross-sectional view of anelectrosurgical device according to another embodiment of the inventiontaken in accordance with line 22-22 of FIG. 21;

FIG. 29 is a schematic close-up front perspective view of anelectrosurgical device according to another embodiment of the invention;

FIG. 30 is a schematic close-up cross-sectional view of the assembly ofthe electrosurgical device of FIG. 29 and tube 19 taken in accordancewith line 12-12 of FIG. 13;

FIG. 31 is a schematic close-up cross-sectional view of theelectrosurgical device of FIG. 29 taken in accordance with line 31-31 ofFIG. 30;

FIG. 32 is a schematic close-up front perspective view of theelectrosurgical device of FIG. 29 with instrument 64 extended;

FIG. 33 is a schematic close-up cross-sectional view of the assembly ofFIG. 30 with instrument 64 extended;

FIG. 34 is a schematic close-up front perspective view of anelectrosurgical device according to another embodiment of the invention;

FIG. 35 is a schematic close-up cross-sectional view of the assembly ofthe electrosurgical device of FIG. 34 and tube 19 taken in accordancewith line 12-12 of FIG. 13;

FIG. 36 is a schematic close-up cross-sectional view of theelectrosurgical device of FIG. 34 taken in accordance with line 36-36 ofFIG. 35;

FIG. 37 is a schematic close-up front perspective view of anelectrosurgical device according to another embodiment of the invention;

FIG. 38 is a schematic close-up cross-sectional view of theelectrosurgical device of FIG. 37 taken in accordance with line 38-38 ofFIG. 39;

FIG. 39 is a schematic close-up cross-sectional view of the assembly ofthe electrosurgical device of FIG. 37 with instrument 64 and tube 19taken in accordance with line 12-12 of FIG. 13;

FIG. 40 is a schematic close-up cross-sectional view of the assembly ofthe electrosurgical device of FIG. 37 with instrument 73 and tube 19taken in accordance with line 12-12 of FIG. 13;

FIG. 41 is a schematic close-up front perspective view of anelectrosurgical device according to another embodiment of the invention;

FIG. 42 is a schematic close-up cross-sectional view of the assembly ofthe electrosurgical device of FIG. 41 and tube 19 taken in accordancewith line 12-12 of FIG. 13;

FIG. 43 is a schematic close-up cross-sectional view of theelectrosurgical device of FIG. 42 taken in accordance with line 43-43 ofFIG. 42;

FIG. 44 is a schematic close-up front perspective view of anelectrosurgical device according to another embodiment of the invention;

FIG. 45 is a schematic close-up rear perspective view of theelectrosurgical device of FIG. 44 with member 51 removed;

FIG. 46 is a schematic close-up cross-sectional view of the assembly ofthe electrosurgical device of FIG. 44 and tube 19 taken in accordancewith line 12-12 of FIG. 13;

FIG. 47 is a schematic close-up cross-sectional view of theelectrosurgical device of FIG. 44 taken in accordance with line 47-47 ofFIG. 46;

FIG. 48 is a schematic close-up front perspective view of anelectrosurgical device according to another embodiment of the invention;

FIG. 49 is a schematic close-up cross-sectional view of the assembly ofthe electrosurgical device of FIG. 48 and tube 19 taken in accordancewith line 12-12 of FIG. 13;

FIG. 50 is a schematic close-up cross-sectional view of theelectrosurgical device of FIG. 48 taken in accordance with line 50-50 ofFIG. 49;

FIG. 51 is a schematic close-up front perspective view of anelectrosurgical device according to another embodiment of the invention;

FIG. 52 is a schematic close-up cross-sectional view of the assembly ofthe electrosurgical device of FIG. 51 and tube 19 taken in accordancewith line 12-12 of FIG. 13;

FIG. 53 is a schematic close-up cross-sectional view of theelectrosurgical device of FIG. 51 taken in accordance with line 53-53 ofFIG. 52;

FIG. 54 is a schematic exploded perspective view of an assembly of anelectrosurgical device according to another embodiment of the inventionand a handle 100;

FIG. 55 is the schematic close-up up cross-sectional view of FIG. 53shown with tissue 20 and with fluid 24;

FIG. 56 is the schematic close-up up cross-sectional view of FIG. 21shown with tissue 20 and with fluid 24;

FIG. 57 is a schematic close-up front perspective view of anelectrosurgical device according to another embodiment of the invention;

FIG. 58 is a schematic close-up rear perspective view of theelectrosurgical device of FIG. 57 with member 51 removed;

FIG. 59 is a schematic close-up cross-sectional view of the assembly ofthe electrosurgical device of FIG. 57 and tube 19 taken in accordancewith line 12-12 of FIG. 13;

FIG. 60 is a schematic close-up cross-sectional view of theelectrosurgical device of FIG. 57 taken in accordance with line 60-60 ofFIG. 59;

FIG. 61 is a schematic close-up front perspective view of anelectrosurgical device according to another embodiment of the invention;

FIG. 62 is a schematic close-up rear perspective view of theelectrosurgical device of FIG. 61 with member 51 removed;

FIG. 63 is a schematic close-up cross-sectional view of the assembly ofthe electrosurgical device of FIG. 61 and tube 19 taken in accordancewith line 12-12 of FIG. 13;

FIG. 64 is a schematic close-up cross-sectional view of the assembly ofthe electrosurgical device of FIG. 61 and tube 19 taken at 90 degrees toline 12-12 of FIG. 13; and

FIG. 65 is a schematic close-up cross-sectional view of theelectrosurgical device of FIG. 61 taken in accordance with line 65-65 ofFIG. 63.

DETAILED DESCRIPTION

Throughout the present description, like reference numerals and lettersindicate corresponding structure throughout the several views, and suchcorresponding structure need not be separately discussed. Furthermore,any particular feature(s) of a particular exemplary embodiment may beequally applied to any other exemplary embodiment(s) of thisspecification as suitable. In other words, features between the variousexemplary embodiments described herein are interchangeable as suitable,and not exclusive.

The invention provides systems, devices and methods that preferablyimprove control of tissue temperature at a tissue treatment site duringa medical procedure. The invention is particularly useful duringsurgical procedures upon tissues of the body, where it is desirable toshrink tissue, coagulate fluids (e.g. oozing blood), and at leastpartially occlude lumens, vessels (e.g. lumen of blood vessels (e.g.arteries, veins), intestines (e.g. absorbent vessels)) and airways (e.g.trachea, bronchi, bronchiole)).

The invention preferably involves the use of electrosurgical procedures,which preferably utilize RF power and electrically conductive fluid totreat tissue. Preferably, a desired tissue temperature range is achievedthrough adjusting parameters, such as conductive fluid flow rate, thataffect the temperature at the tissue/electrode interface. Preferably,the device achieves a desired tissue temperature utilizing a desiredpercentage boiling of the conductive solution at the tissue/electrodeinterface.

In one embodiment, the invention provides a control device, the devicecomprising a flow rate controller that receives a signal indicatingpower applied to the system, and adjusts the flow rate of conductivefluid from a fluid source to an electrosurgical device. The inventionalso contemplates a control system comprising a flow rate controller, ameasurement device that measures power applied to the system, and a pumpthat provides fluid at a selected flow rate.

The invention will be discussed generally with reference to FIG. 1. FIG.1 shows a block diagram of one exemplary embodiment of a system of theinvention. Preferably, as shown in FIG. 1, an electrically conductivefluid is provided from a fluid source 1, through a fluid line 2, to apump 3, which has an outlet fluid line 4 a that is connected as an inputfluid line 4 b to electrosurgical device 5. In a preferred embodiment,the outlet fluid line 4 a and the input fluid line 4 b are flexible andcomprise a polymer, such as polyvinylchloride (PVC), while theconductive fluid comprises a saline solution. More preferably, thesaline comprises sterile, and even more preferably, normal saline.Although the description herein will specifically describe the use ofsaline as the fluid, other electrically conductive fluids, as well asnon-conductive fluids, can be used in accordance with the invention.

For example, in addition to the conductive fluid comprising physiologicsaline (also known as “normal” saline, isotonic saline or 0.9% sodiumchloride (NaCl) solution), the conductive fluid may comprise hypertonicsaline solution, hypotonic saline solution, Ringers solution (aphysiologic solution of distilled water containing specified amounts ofsodium chloride, calcium chloride, and potassium chloride), lactatedRinger's solution (a crystalloid electrolyte sterile solution ofdistilled water containing specified amounts of calcium chloride,potassium chloride, sodium chloride, and sodium lactate), Locke-Ringer'ssolution (a buffered isotonic solution of distilled water containingspecified amounts of sodium chloride, potassium chloride, calciumchloride, sodium bicarbonate, magnesium chloride, and dextrose), or anyother electrolyte solution. In other words, a solution that conductselectricity via an electrolyte, a substance (salt, acid or base) thatdissociates into electrically charged ions when dissolved in a solvent,such as water, resulting solution comprising an ionic conductor.

While a conductive fluid is preferred, as will become more apparent withfurther reading of this specification, the fluid may also comprise anelectrically non-conductive fluid. The use of a non-conductive fluid isless preferred to that of a conductive fluid as the non-conductive fluiddoes not conduct electricity. However, the use of a non-conductive fluidstill provides certain advantages over the use of a dry electrodeincluding, for example, reduced occurrence of tissue sticking to theelectrode. Therefore, it is also within the scope of the invention toinclude the use of a non-conducting fluid, such as, for example,dionized water.

Energy to heat tissue is provided from energy source, such as anelectrical generator 6 which preferably provides RF alternating currentenergy via a cable 7 to energy source output measurement device, such asa power measurement device 8 that measures the RF alternating currentelectrical power. In one exemplary embodiment, preferably the powermeasurement device 8 does not turn the power off or on, or alter thepower in any way. A power switch 15 connected to the generator 6 ispreferably provided by the generator manufacturer and is used to turnthe generator 6 on and off. The power switch 15 can comprise any switchto turn the power on and off, and is commonly provided in the form of afootswitch or other easily operated switch, such as a switch 15 amounted on the electrosurgical device 5. The power switch 15 or 15 a mayalso function as a manually activated device for increasing ordecreasing the rate of energy provided from the surgical device 5.Alternatively, internal circuitry and other components of the generator6 may be used for automatically increasing or decreasing the rate ofenergy provided from the surgical device 5. A cable 9 preferably carriesRF energy from the power measurement device 8 to the electrosurgicaldevice 5. Power, or any other energy source output, is preferablymeasured before it reaches the electrosurgical device 5.

For the situation where capacitation and induction effects arenegligibly small, from Ohm's law, power P, or the rate of energydelivery (e.g. joules/sec), may be expressed by the product of currenttimes voltage (i.e. I×V), the current squared times resistance (i.e.I²×R), or the voltage squared divided by the resistance (i.e. V²/R);where the current I may be measured in amperes, the voltage V may bemeasured in volts, the electrical resistance R may be measured in ohms,and the power P may be measured in watts (joules/sec). Given that powerP is a function of current I, voltage V, and resistance R as indicatedabove, it should be understood, that a change in power P is reflectiveof a change in at least one of the input variables. Thus, one mayalternatively measure changes in such input variables themselves, ratherthan power P directly, with such changes in the input variablesmathematically corresponding to a changes in power P as indicated above.

As to the frequency of the RF electrical energy, it is preferablyprovided within a frequency band (i.e. a continuous range of frequenciesextending between two limiting frequencies) in the range between andincluding about 9 kHz (kilohertz) to 300 GHz (gigahertz). Morepreferably, the RF energy is provided within a frequency band in therange between and including about 50 kHz (kilohertz) to 50 MHz(megahertz). Even more preferably, the RF energy is provided within afrequency band in the range between and including about 200 kHz(kilohertz) to 2 MHz (megahertz). Most preferably, RF energy is providedwithin a frequency band in the range between and including about 400 kHz(kilohertz) to 600 kHz (kilohertz). Further, it should also beunderstood that, for any frequency band identified above, the range offrequencies may be further narrowed in increments of 1 (one) hertzanywhere between the lower and upper limiting frequencies.

While RF electrical energy is preferred, it should be understood thatthe electrical energy (i.e., energy made available by the flow ofelectric charge, typically through a conductor or by self-propagatingwaves) may comprise any frequency of the electromagnetic spectrum (i.e.the entire range of radiation extending in frequency from 10²³ hertz to0 hertz) and including, but not limited to, gamma rays, x-rays,ultraviolet radiation, visible light, infrared radiation, microwaves,and any combinations thereof.

With respect to the use of electrical energy, heating of the tissue ispreferably performed by means of resistance heating. In other words,increasing the temperature of the tissue as a result of electric currentflow through the tissue, with the electrical energy being absorbed fromthe voltage and transformed into thermal energy (i.e. heat) viaaccelerated movement of ions as a function of the tissue's electricalresistance.

Heating with electrical energy may also be performed by means ofdielectric heating (capacitation). In other words, increasing thetemperature of the tissue through the dissipation of electrical energyas a result of internal dielectric loss when the tissue is placed in avarying electric field, such as a high-frequency (e.g. microwave),alternating electromagnetic field. Dielectric loss is the electricalenergy lost as heat in the polarization process in the presence of theapplied electric field. In the case of an alternating current field, theenergy is absorbed from the alternating current voltage and converted toheat during the polarization of the molecules.

However, it should be understood that energy provided to heat the tissuemay comprise surgical devices other than electrosurgical devices, energysources other than generators, energy forms other than electrical energyand mechanisms other than resistance heating. For example, providingthermal energy to the tissue from energy source with a difference (e.g.higher) in temperature. Such may be provided, for example, to the tissuefrom a heated device, which heats tissue through direct contact with theenergy source (conduction), heats through contact with a flowing fluid(convection), or from a remote heat source (radiation).

Also, for example, providing energy to the tissue may be provided viamechanical energy which is transformed into thermal energy viaaccelerated movement of the molecules, such as by mechanical vibrationprovided, for example, by energy source such as a transducer containinga piezoelectric substance (e.g., a quartz-crystal oscillator) thatconverts high-frequency electric current into vibrating ultrasonic waveswhich may be used by, for example, an ultrasonic surgical device.

Also, for example, providing energy to the tissue may be provided viaradiant energy (i.e. energy which is transmitted by radiation/waves)which is transformed into thermal energy via absorption of the radiantenergy by the tissue. Preferably the radiation/waves compriseelectromagnetic radiation/waves which include, but is not limited to,radio waves, microwaves, infrared radiation, visible light radiation,ultraviolet radiation, x-rays and gamma rays. More preferably, suchradiant energy comprises energy with a frequency of 3×10¹¹ hertz to3×10¹⁶ hertz (i.e. the infrared, visible, and ultraviolet frequencybands of the electromagnetic spectrum). Also preferably theelectromagnetic waves are coherent and the electromagnetic radiation isemitted from energy source such as a laser device. A flow ratecontroller 11 preferably includes a selection switch 12 that can be setto achieve desired levels of percentage fluid boiling (for example,100%, 98%, 80% boiling). Preferably, the flow rate controller 11receives an input signal 10 from the power measurement device 8 andcalculates an appropriate mathematically predetermined fluid flow ratebased on percentage boiling indicated by the selection switch 12. In apreferred embodiment, a fluid switch 13 is provided so that the fluidsystem can be primed (e.g. air eliminated) before turning the generator6 on. The output signal 16 of the flow rate controller 11 is preferablysent to the pump 3 motor to regulate the flow rate of conductive fluid,and thereby provide an appropriate fluid flow rate which corresponds tothe amount of power being delivered.

In one exemplary embodiment, the invention comprises a flow ratecontroller that is configured and arranged to be connected to a sourceof RF power, and a source of fluid, for example, a source of conductivefluid. The device of the invention receives information about the levelof RF power applied to an electrosurgical device, and adjusts the flowrate of the fluid to the electrosurgical device, thereby controllingtemperature at the tissue treatment site.

In another exemplary embodiment, elements of the system are physicallyincluded together in one electronic enclosure. One such embodiment isshown by enclosure within the outline box 14 of FIG. 1. In theillustrated embodiment, the pump 3, flow rate controller 11, and powermeasurement device 8 are enclosed within an enclosure, and theseelements are connected through electrical connections to allow signal 10to pass from the power measurement device 8 to the flow rate controller11, and signal 16 to pass from the flow rate controller 11 to the pump3. Other elements of a system can also be included within one enclosure,depending upon such factors as the desired application of the system,and the requirements of the user.

The pump 3 can be any suitable pump used in surgical procedures toprovide saline or other fluid at a desired flow rate. Preferably, thepump 3 comprises a peristaltic pump. With a rotary peristaltic pump,typically a fluid is conveyed within the confines of a flexible tube bywaves of contraction placed externally on the tube which are producedmechanically, typically by rotating rollers which squeeze the flexibletubing against a support intermittently. Alternatively, with a linearperistaltic pump, typically a fluid is conveyed within the confines of aflexible tube by waves of contraction placed externally on the tubewhich are produced mechanically, typically by a series of compressionfingers or pads which squeeze the flexible tubing against a supportsequentially. Peristaltic pumps are generally preferred for use as theelectro-mechanical force mechanism (e.g. rollers driven by electricmotor) does not make contact the fluid, thus reducing the likelihood ofinadvertent contamination.

Alternatively, pump 3 can be a “syringe pump”, with a built-in fluidsupply. With such a pump, typically a filled syringe is located on anelectro-mechanical force mechanism (e.g. ram driven by electric motor)which acts on the plunger of the syringe to force delivery of the fluidcontained therein. Alternatively, the syringe pump may comprise adouble-acting syringe pump with two syringes such that they can drawsaline from a reservoir, either simultaneously or intermittently. With adouble acting syringe pump, the pumping mechanism is generally capableof both infusion and withdrawal. Typically, while fluid is beingexpelled from one syringe, the other syringe is receiving fluid thereinfrom a separate reservoir. In this manner, the delivery of fluid remainscontinuous and uninterrupted as the syringes function in series.Alternatively, it should be understood that a multiple syringe pump withtwo syringes, or any number of syringes, may be used in accordance withthe invention.

Furthermore, fluid, such as conductive fluid, can also be provided froman intravenous (IV) bag full of saline that flows under the influence(i.e. force) of gravity. In such a manner, the fluid may flow directlyto the electrosurgical device 5, or first to the pump 3 located therebetween. Alternatively, fluid from a fluid source such as an IV bag canbe provided through an IV flow controller that may provide a desiredflow rate by adjusting the cross sectional area of a flow orifice (e.g.lumen of the connective tubing with the electrosurgical device) whilesensing the flow rate with a sensor such as an optical drop counter.Furthermore, fluid from a fluid source such as an IV bag an be providedthrough a manually or automatically activated device such as a flowcontroller, such as a roller clamp, which also adjusts the crosssectional area of a flow orifice and may be adjusted manually by, forexample, the user of the device in response to their visual observation(e.g. fluid boiling) at the tissue treatment site or a pump.

Similar pumps can be used in connection with the invention, and theillustrated embodiments are exemplary only. The precise configuration ofthe pump 3 is not critical to the invention. For example, pump 3 mayinclude other types of infusion and withdrawal pumps. Furthermore, pump3 may comprise pumps which may be categorized as piston pumps, rotaryvane pumps (e.g. blower, axial impeller, centrifugal impeller),cartridge pumps and diaphragm pumps. In some embodiments, the pump canbe substituted with any type of flow controller, such as a manual rollerclamp used in conjunction with an IV bag, or combined with the flowcontroller to allow the user to control the flow rate of conductivefluid to the device. Alternatively, a valve configuration can besubstituted for pump 3.

Furthermore, similar configurations of the system can be used inconnection with the invention, and the illustrated embodiments areexemplary only. For example, the fluid source 1 pump 3, generator 6,power measurement device 8 or flow rate controller 11, or any othercomponents of the system not expressly recited above, may comprise aportion of the electrosurgical device 5. For example, in one exemplaryembodiment the fluid source may comprise a compartment of theelectrosurgical device 5 which contains fluid, as indicated at referencecharacter 1 a. In another exemplary embodiment, the compartment may bedetachably connected to the electrosurgical device 5, such as a canisterwhich may be attached via threaded engagement with the device 5. In yetanother exemplary embodiment, the compartment may be configured to holda pre-filled cartridge of fluid, rather than the fluid directly.

Also for example, with regards to the generator, energy source, such asa direct current (DC) battery used in conjunction with invertercircuitry and a transformer to produce alternating current at aparticular frequency, may comprise a portion of the electrosurgicaldevice 5, as indicated at reference character 6 a. In one embodiment thebattery element of the energy source may comprise a rechargeablebattery. In yet another exemplary embodiment, the battery element may bedetachably connected to the electrosurgical device 5, such as forrecharging. The components of the system will now be described infurther detail. From the specification, it should be clear that any useof the terms “distal” and “proximal” are made in reference from the userof the device, and not the patient.

The flow rate controller 11 controls the rate of flow from the fluidsource 1. Preferably, the rate of fluid flow from the fluid source 1 isbased upon the amount of RF power provided from the generator 6 to theelectrosurgical device 5. In other words, as shown in FIG. 2, preferablythere is a relationship between the rate of fluid flow and the RF poweras indicated by the X- and Y-axes of the schematic graph. Moreprecisely, as shown in FIG. 2, the relationship between the rate offluid flow and RF power may be expressed as a direct, linearrelationship. The flow rate of conductive fluid, such as saline,interacts with the RF power and various modes of heat transfer away fromthe target tissue, as described herein.

Throughout this disclosure, when the terms “boiling point of saline”,“vaporization point of saline”, and variations thereof are used, what isintended is the boiling point of the water in the saline solution.

FIG. 2 shows a schematic graph that describes the relationship betweenthe flow rate of saline, RF power to tissue, and regimes of boiling asdetailed below. Based on a simple one-dimensional lumped parameter modelof the heat transfer, the peak tissue temperature can be estimated, andonce tissue temperature is estimated, it follows directly whether it ishot enough to boil saline.P=ΔT/R+ρc _(ρ) Q ₁ ΔT+ρQ _(b) h _(v)  (1)where P=the total RF electrical power that is converted into heat.

Conduction. The first term [ΔT/R] in equation (1) is heat conducted toadjacent tissue, represented as 70 in FIG. 2, where:

-   -   ΔT=(T−T_(∞)) the difference in temperature between the peak        tissue temperature (T) and the normal temperature (T_(∞)) of the        body tissue (° C.). Normal temperature of the body tissue is        generally 37° C.; and    -   R=Thermal resistance of surrounding tissue, the ratio of the        temperature difference to the heat flow (° C./watt).

This thermal resistance can be estimated from published data gathered inexperiments on human tissue (Phipps, J. H., “Thermometry studies withbipolar diathermy during hysterectomy,” Gynaecological Endoscopy, 3:5-7(1994)). As described by Phipps, Kleppinger bipolar forceps were usedwith an RF power of 50 watts, and the peak tissue temperature reached320° C. For example, using the energy balance of equation (1), andassuming all the RF heat put into tissue is conducted away, then R canbe estimated:R=ΔT/P=(320−37)/50=5.7≈6° C./watt

However, it is undesirable to allow the tissue temperature to reach 320°C., since tissue will become desiccated. At a temperature of 320° C.,the fluid contained in the tissue is typically boiled away, resulting inthe undesirable tissue effects described herein. Rather, it is preferredto keep the peak tissue temperature at no more than about 100° C. toinhibit desiccation of the tissue. Assuming that saline boils at about100° C., the first term in equation (1) (ΔT/R) is equal to(100−37)/6=10.5 watts. Thus, based on this example, the maximum amountof heat conducted to adjacent tissue without any significant risk oftissue desiccation is 10.5 watts.

Referring to FIG. 2, RF power to tissue is represented on the X-axis asP (watts) and flow rate of saline (cc/min) is represented on the Y-axisas Q. When the flow rate of saline equals zero (Q=0), there is an“offset” RF power that shifts the origin of the sloped lines 76, 78, and80 to the right. This offset is the heat conducted to adjacent tissue.For example, using the calculation above for bipolar forceps, thisoffset RF power is about 10.5 watts. If the power is increased abovethis level with no saline flow, the peak tissue temperature can risewell above 100° C., resulting in tissue desiccation from the boiling offof water in the cells of the tissue.

Convection. The second term [ρc_(ρ)Q₁ΔT] in equation (1) is heat used towarm up the flow of saline without boiling the saline, represented as 72in FIG. 2, where:

-   -   ρ=Density of the saline fluid that gets hot but does not boil        (approximately 1.0 gm/cm³);    -   c_(ρ)=Specific heat of the saline (approximately 4.1        watt-sec/gm-° C.);    -   Q₁=Flow rate of the saline that is heated (cm³/sec); and    -   ΔT=Temperature rise of the saline. Assuming that the saline is        heated to body temperature before it gets to the electrode, and        that the peak saline temperature is similar to the peak tissue        temperature, this is the same ΔT as for the conduction        calculation above.

The onset of boiling can be predicted using equation (1) with the lastterm on the right set to zero (no boiling) (ρQ_(b)h_(v)=0), and solvingequation (1) for Q₁ leads to:Q ₁ =[P−ΔT/R]/ρc _(ρ) ΔT  (2)

This equation defines the line shown in FIG. 2 as the line of onset ofboiling 76.

Boiling. The third term [ρQ_(b)h_(v)] in equation (1) relates to heatthat goes into converting the water in liquid saline to water vapor, andis represented as 74 in FIG. 2, where:

-   -   Q_(b)=Flow rate of saline that boils (cm³/sec); and    -   h_(v)=Heat of vaporization of saline (approximately 2,000        watt-sec/gm).

A flow rate of only 1 cc/min will absorb a significant amount of heat ifit is completely boiled, or about ρQ_(b)h_(v)=(1) (1/60) (2,000)=33.3watts. The heat needed to warm this flow rate from body temperature to100° C. is much less, or ρc_(ρ)Q₁ΔT=(1) (4.1) (1/60) (100−37)=4.3 watts.In other words, the most significant factor contributing to heattransfer from a wet electrode device can be fractional boiling. Thepresent invention recognizes this fact and exploits it.

Fractional boiling can be described by equation (3) below:

$\begin{matrix}{Q_{1} = \frac{\left\{ {P - {\Delta\;{T/R}}} \right\}}{\left\{ {{\rho\; c_{p}\Delta\; T} + {\rho\; h_{v}{Q_{b}/Q_{l}}}} \right\}}} & (3)\end{matrix}$

If the ratio of Q_(b)/Q₁ is 0.50 this is the 50% boiling line 78 shownin FIG. 2. If the ratio is 1.0 this is the 100% boiling line 80 shown inFIG. 2.

As indicated previously in the specification, using a fluid to coupleenergy to tissue inhibits such undesirable effects as sticking,desiccation, smoke production and char formation, and that one keyfactor is inhibiting tissue desiccation, which occur if the tissuetemperature exceeds 100° C. and all the intracellular water boils away,leaving the tissue extremely dry and much less electrically conductive.

As shown in FIG. 2, one control strategy or mechanism which can beemployed for the electrosurgical device 5 is to adjust the power P andflow rate Q such that the power P used at a corresponding flow rate Q isequal to or less than the power P required to boil 100% of the fluid anddoes not exceed the power P required to boil 100% of the fluid. In otherwords, this control strategy targets using the electrosurgical device 5in the regions of FIG. 2 identified as T<100° C. and T=100° C., andincludes the 100% boiling line 80. Stated another way, this controlstrategy targets not using the electrosurgical device 5 only in theregion of FIG. 2 identified as T>>100° C.

Another control strategy that can be used for the electrosurgical device5 is to operate the device 5 in the region T<100° C., but at high enoughtemperature to shrink tissue containing Type I collagen (e.g., walls ofblood vessels, bronchi, bile ducts, etc.), which shrinks when exposed toabout 85° C. for an exposure time of 0.01 seconds, or when exposed toabout 65° C. for an exposure time of 15 minutes. An exemplary targettemperature/time for tissue shrinkage is about 75° C. with an exposuretime of about 1 second. As discussed herein, a determination of the highend of the scale (i.e., when the fluid reaches 100° C.) can be made bythe phase change in the fluid from liquid to vapor. However, adetermination at the low end of the scale (e.g., when the fluid reaches,for example, 75° C. for 1 second) requires a different mechanism as thetemperature of the fluid is below the boiling temperature and no suchphase change is apparent. In order to determine when the fluid reaches atemperature that will facilitate tissue shrinkage, for example 75° C., athermochromic material, such as a thermochromic dye (e.g., leuco dye),may be added to the fluid. The dye can be formulated to provide a firstpredetermined color to the fluid at temperatures below a thresholdtemperature, such as 75° C., then, upon heating above 75° C., the dyeprovides a second color, such as clear, thus turning the fluid clear(i.e. no color or reduction in color). This color change may be gradual,incremental, or instant. Thus, a change in the color of the fluid, froma first color to a second color (or lack thereof) provides a visualindication to the user of the electrosurgical device 5 as to when athreshold fluid temperature below boiling has been achieved.Thermochromic dyes are available, for example, from Color ChangeCorporation, 1740 Cortland Court, Unit A, Addison, Ill. 60101.

It is also noted that the above mechanism (i.e., a change in the colorof the fluid due to a dye) may also be used to detect when the fluidreaches a temperature which will facilitate tissue necrosis; thisgenerally varies from about 60° C. for an exposure time of 0.01 secondsand decreasing to about 45° C. for an exposure time of 15 minutes. Anexemplary target temperature/time for tissue necrosis is about 55° C.for an exposure time of about 1 second.

In order to reduce coagulation time, use of the electrosurgical device 5in the region T=100° C. of FIG. 2 is preferable to use of theelectrosurgical device 5 in the region T<100° C. Consequently, as shownin FIG. 2, another control strategy which may be employed for theelectrosurgical device 5 is to adjust the power P and flow rate Q suchthat the power P used at a corresponding flow rate Q is equal to or morethan the power P required to initiate boiling of the fluid, but stillless than the power P required to boil 100% of the fluid. In otherwords, this control strategy targets using the electrosurgical device 5in the region of FIG. 2 identified as T=100° C., and includes the linesof the onset of boiling 76 and 100% boiling line 80. Stated another way,this control strategy targets use using the electrosurgical device 5 onor between the lines of the onset of boiling 76 and 100% boiling line80, and not using the electrosurgical device 5 in the regions of FIG. 2identified as T<100° C. and T>>100° C.

For consistent tissue effect, it is desirable to control the saline flowrate so that it is always on a “line of constant % boiling” as, forexample, the line of the onset of boiling 76 or the 100% boiling line 80or any line of constant % boiling located in between (e.g. 50% boilingline 78) as shown in FIG. 2. Consequently, another control strategy thatcan be used for the electrosurgical device 5 is to adjust power P andflow rate Q such that the power P used at a corresponding flow rate Qtargets a line of constant % boiling.

It should be noted, from the preceding equations, that the slope of anyline of constant % boiling is known. For example, for the line of theonset of boiling 76, the slope of the line is given by (ρc_(p)ΔT), whilethe slope of the 100% boiling line 80 is given by 1/(ρc_(p)ΔT+ρh_(v)).As for the 50% boiling line 78, for example, the slope is given by1/(ρc_(p)ΔT+ρh_(v)0.5).

If, upon application of the electrosurgical device 5 to the tissue,boiling of the fluid is not detected, such indicates that thetemperature is less than 100° C. as indicated in the area of FIG. 2, andthe flow rate Q must be decreased to initiate boiling. The flow rate Qmay then decreased until boiling of the fluid is first detected, atwhich time the line of the onset of boiling 76 is transgressed and thepoint of transgression on the line 76 is determined. From thedetermination of a point on the line of the onset of boiling 76 for aparticular power P and flow rate Q, and the known slope of the line 76as outlined above (i.e. 1/ρc_(p)ΔT), it is also possible to determinethe heat conducted to adjacent tissue 70.

Conversely, if upon application of the electrosurgical device 5 to thetissue, boiling of the fluid is detected, such indicates that thetemperature is approximately equal to 100° C. as indicated in the areasof FIG. 2, and the flow rate Q must be increased to reduce boiling untilboiling stops, at which time the line of the onset of boiling 76 istransgressed and the point of transgression on the line 76 determined.As with above, from the determination of a point on the line of theonset of boiling 76 for a particular power P and flow rate Q, and theknown slope of the line 76, it is also possible to determine the heatconducted to adjacent tissue 70.

With regards to the detection of boiling of the fluid, such may bephysically detected by the user (e.g. visually by the naked eye) of theelectrosurgical device 5 in the form of either bubbles or steam evolvingfrom the fluid coupling at the electrode/tissue interface.Alternatively, such a phase change (i.e. from liquid to vapor orvice-versa) may be measured by a sensor which preferably senses eitheran absolute change (e.g. existence or non-existence of boiling withbinary response such as yes or no) or a change in a physical quantity orintensity and converts the change into a useful input signal for aninformation-gathering system. For example, the phase change associatedwith the onset of boiling may be detected by a pressure sensor, such asa pressure transducer, located on the electrosurgical device 5.Alternatively, the phase change associated with the onset of boiling maybe detected by a temperature sensor, such as a thermistor orthermocouple, located on the electrosurgical device 5, such as adjacentto the electrode. Also alternatively, the phase change associated withthe onset of boiling may be detected by a change in the electricproperties of the fluid itself. For example, a change in the electricalresistance of the fluid may be detected by an ohm meter; a change in theamperage may be measured by an amp meter; as change in the voltage maybe detected by a volt meter; and a change in the power may be determinedby a power meter.

Yet another control strategy which may be employed for theelectrosurgical device 5 is to eliminate the heat conduction term ofequation (1) (i.e. ΔT/R). Since the amount of heat conducted away toadjacent tissue can be difficult to precisely predict, as it may vary,for example, by tissue type, it may be preferable, from a control pointof view, to assume the worst case situation of zero heat conduction, andprovide enough saline so that if necessary, all the RF power could beused to heat up and boil the saline, thus providing that the peak tissuetemperature will not go over 100° C. a significant amount. Thissituation is shown in the schematic graph of FIG. 3.

Stated another way, if the heat conducted to adjacent tissue 70 isoverestimated, the power P required to intersect the 100% boiling line80 will, in turn, be overestimated and the 100% boiling line 80 will betransgressed into the T>>100° C. region of FIG. 2, which is undesirableas established above. Thus, assuming the worse case situation of zeroheat conduction provides a “safety factor” to avoid transgressing the100% boiling line 80. Assuming heat conduction to adjacent tissue 70 tobe zero also provides the advantage of eliminating the only term fromequation (1) which is tissue dependent, i.e., depends on tissue type.Thus, provided ρ, c_(p), ΔT, and h_(v) are known as indicated above, theequation of the line for any line of constant % boiling is known. Thus,for example, the 98% boiling line, 80% boiling line, etc. can bedetermined in response to a corresponding input from the selectionswitch 12. In order to promote flexibility, it should be understood thatthe input from the selection switch preferably may comprise anypercentage of boiling. Preferably the percentage of boiling may beselected in single percent increments (i.e. 100%, 99%, 98%, etc.).

Upon determination of the line of the onset of boiling 76, the 100%boiling line 80 or any line of constant % boiling there between, it isgenerally desirable to control the flow rate Q so that it is always on aparticular line of constant % boiling for consistent tissue effect. Insuch a situation, the flow rate controller 11 will adjust the flow rateQ of the fluid to reflect changes in power P provided by the generator6, as discussed in greater detail below. For such a use the flow ratecontroller may be set in a line of constant boiling mode, upon which the% boiling is then correspondingly selected.

As indicated above, it is desirable to control the saline flow rate Q sothat it is always on a line of constant % boiling for consistent tissueeffect. However, the preferred line of constant % boiling may vary basedon the type of electrosurgical device 5. For example, if the device is amonopolar stasis device and shunting through saline is not an issue,then it can be preferable to operate close to or directly on, but notover the line of the onset of boiling, such as 76 a in FIG. 3. Thispreferably keeps tissue as hot as possible without causing desiccation.Alternatively, if the device has coaptive bipolar opposing jaws andshunting of electrical energy from one jaw to the other jaw throughexcess saline is an issue, then it can be preferable to operate along aline of constant boiling, such as line 78 a in FIG. 3, the 50% line.This simple proportional control will have the flow rate determined byequation (4), where K is the proportionality constant:Q ₁ =K×P  (4)

In essence, when power P goes up, the flow rate Q will beproportionately increased. Conversely, when power P goes down, the flowrate Q will be proportionately decreased.

The proportionality constant K is primarily dependent on the fraction ofsaline that boils, as shown in equation (5), which is equation (3)solved for K after eliminating P using equation (4), and neglecting theconduction term (ΔT/R):

$\begin{matrix}{K = \frac{1}{\left\{ {{\rho\; c_{p}\Delta\; T} + {\rho\; h_{v}{Q_{b}/Q_{l}}}} \right\}}} & (5)\end{matrix}$

Thus, the present invention provides a method of controlling boiling offluid, such as a conductive fluid, at the tissue/electrode interface. Ina preferred embodiment, this provides a method of treating tissuewithout use of tissue sensors, such as temperature or impedance sensors.Preferably, the invention can control boiling of conductive fluid at thetissue/electrode interface and thereby control tissue temperaturewithout the use of feedback loops.

In describing the control strategy of the present invention describedthus far, focus has been drawn to a steady state condition. However, theheat required to warm the tissue to the peak temperature (T) may beincorporated into equation (1) as follows:P=ΔT/R+ρc _(ρ) Q ₁ ΔT+ρQ _(b) h _(v) +ρc _(ρ) VΔT/Δt  (6)

where ρc_(ρ)VΔT/Δt represents the heat required to warm the tissue tothe peak temperature (T) 68 and where:

-   -   ρ=Density of the saline fluid that gets hot but does not boil        (approximately 1.0 gm/cm³);    -   c_(ρ)=Specific heat of the saline (approximately 4.1        watt-sec/gm-° C.);    -   V=Volume of treated tissue    -   ΔT=(T−T_(∞)) the difference in temperature between the peak        tissue temperature (T) and the normal temperature (T_(∞)) of the        body tissue (° C.). Normal temperature of the body tissue is        generally 37° C.; and    -   Δt=(t−t_(∞)) the difference in time to achieve peak tissue        temperature (T) and the normal temperature (T_(∞)) of the body        tissue (° C.).

The inclusion of the heat required to warm the tissue to the peaktemperature (T) in the control strategy is graphically represented at 68in FIG. 2A. With respect to the control strategy, the effects of theheat required to warm the tissue to the peak temperature (T) 68 shouldbe taken into account before flow rate Q adjustment being undertaken todetect the location of the line of onset of boiling 76. In other words,the flow rate Q should not be decreased in response to a lack of boilingbefore at least a quasi-steady state has been achieved as the locationof the line of onset of boiling 76 will continue to move during thetransitory period. Otherwise, if the flow rate Q is decreased during thetransitory period, it may be possible to decrease the flow Q to a pointpast the line of onset of boiling 76 and continue past the 100% boilingline 80 which is undesirable. In other words, as temperature (T) isapproached the heat 68 diminishes towards zero such that the lines ofconstant boiling shift to the left towards the Y-axis.

FIG. 4 shows an exemplary graph of flow rate Q versus % boiling for asituation where the RF power P is 75 watts. The percent boiling isrepresented on the X-axis, and the saline flow rate Q (cc/min) isrepresented on the Y-axis. According to this example, at 100% boilingthe most desirable predetermined saline flow rate Q is 2 cc/min. Alsoaccording to this example, flow rate Q versus % boiling at the remainingpoints of the graft illustrates a non-linear relationship as follows:

TABLE 1 % Boiling and Flow Rate Q (cc/min) at RF Power P of 75 watts  0%17.4 10% 9.8 20% 6.8 30% 5.2 40% 4.3 50% 3.6 60% 3.1 70% 2.7 80% 2.4 90%2.2 100%  2.0

Typical RF generators used in the field have a power selector switch to300 watts of power, and on occasion some have been found to beselectable up to 400 watts of power. In conformance with the abovemethodology, at 0% boiling with a corresponding power of 300 watts, thecalculated flow rate Q is 69.7 cc/min and with a corresponding power of400 watts the calculated flow rate Q is 92.9 cc/min. Thus, when usedwith typical RF generators in the field, a fluid flow rate Q of about100 cc/min or less with the present invention is expected to suffice forthe vast majority of applications.

As discussed herein, RF energy delivery to tissue can be unpredictableand vary with time, even though the generator has been “set” to a fixedwattage. The schematic graph of FIG. 5 shows the general trends of theoutput curve of a typical general-purpose generator, with the outputpower changing as load (tissue plus cables) impedance Z changes. Loadimpedance Z (in ohms) is represented on the X-axis, and generator outputpower P (in watts) is represented on the Y-axis. In the illustratedembodiment, the electrosurgical power (RF) is set to 75 watts in abipolar mode. As shown in the figure, the power will remain constant asit was set as long as the impedance Z stays between two cut-offs, lowand high, of impedance, that is, for example, between 50 ohms and 300ohms in the illustrated embodiment. Below load impedance Z of 50 ohms,the power P will decrease, as shown by the low impedance ramp 82 a.Above load impedance Z of 300 ohms, the power P will decrease, as shownby the high impedance ramp 82 b. Of particular interest tosaline-enhanced electrosurgery is the low impedance cut-off (lowimpedance ramp 82 a), where power starts to ramp down as impedance Zdrops further. This change in output is invisible to the user of thegenerator and not evident when the generator is in use, such as in anoperating room.

FIG. 6 shows the general trend of how tissue impedance generally changeswith time for saline-enhanced electrosurgery. As tissue heats up, thetemperature coefficient of the tissue and saline in the cells is suchthat the tissue impedance decreases until a steady-state temperature isreached upon which time the impedance remains constant. Thus, as tissueheats up, the load impedance Z decreases, potentially approaching theimpedance Z cut-off of 50 ohms. If tissue is sufficiently heated, suchthat the low impedance cut-off is passed, the power P decreases alongthe lines of the low impedance ramp 82 a of FIG. 5.

Combining the effects shown in FIG. 5 and FIG. 6, it becomes clear thatwhen using a general-purpose generator set to a “fixed” power, theactual power delivered can change dramatically over time as tissue heatsup and impedance drops. Looking at FIG. 5, if the impedance Z drops from100 to 75 ohms over time, the power output would not change because thecurve is “flat” in that region of impedances. If, however, the impedanceZ drops from 75 to 30 ohms one would transgress the low impedancecut-off and “turn the corner” onto the low impedance ramp 82 a portionof the curve and the power output would decrease dramatically.

According to one exemplary embodiment of the invention, the controldevice, such as flow rate controller 11, receives a signal indicatingthe drop in actual power delivered to the tissue and adjusts the flowrate Q of saline to maintain the tissue/electrode interface at a desiredtemperature. In a preferred embodiment, the drop in actual power Pdelivered is sensed by the power measurement device 8 (shown in FIG. 1),and the flow rate Q of saline is decreased by the flow rate controller11 (also shown in FIG. 1). Preferably, this reduction in saline flowrate Q allows the tissue temperature to stay as hot as possible withoutdesiccation. If the control device was not in operation and the flowrate Q allowed to remain higher, the tissue would be over-cooled at thelower power input. This would result in decreasing the temperature ofthe tissue at the treatment site.

The flow rate controller 11 of FIG. 1 can be a simple “hard-wired”analog or digital device that requires no programming by the user or themanufacturer. The flow rate controller 11 can alternatively include aprocessor, with or without a storage medium, in which the determinationprocedure is performed by software, hardware, or a combination thereof.In another embodiment, the flow rate controller 11 can includesemi-programmable hardware configured, for example, using a hardwaredescriptive language, such as Verilog. In another embodiment, the flowrate controller 11 of FIG. 1 is a computer, microprocessor-drivencontroller with software embedded. In yet another embodiment, the flowrate controller 11 can include additional features, such as a delaymechanism, such as a timer, to automatically keep the saline flow on forseveral seconds after the RF is turned off to provide a post-coagulationcooling of the tissue or “quench,” which can increase the strength ofthe tissue seal. Also, in another embodiment, the flow rate controller11 can include a delay mechanism, such as a timer, to automatically turnon the saline flow several seconds before the RF is turned on to inhibitthe possibility of undesirable effects as sticking, desiccation, smokeproduction and char formation. Also in another embodiment, the flow ratecontroller 11 can include a low level flow standby mechanism, such as avalve, which continues the saline flow at a standby flow level (whichprevents the flow rate from going to zero when the RF power is turnedoff) below the surgical flow level ordinarily encountered during use ofthe electrosurgical device 5.

An exemplary electrosurgical device of the present invention which maybe used in conjunction with the system of the present invention is shownat reference character 5 a in FIG. 9, and more particularly in FIGS.7-16. While various electrosurgical devices of the present invention aredescribed with reference to use with the remainder of the system of theinvention, it should be understood that the description of thecombination is for purposes of illustrating the remainder of the systemof the invention only. Consequently, it should be understood that theelectrosurgical devices of the present invention can be used alone, orin conjunction with the remainder of the system of the invention, orthat a wide variety of electrosurgical devices can be used in connectionwith the remainder of the system of the invention.

As shown in FIGS. 7 and 8, electrosurgical device 5 a is preferably usedin conjunction with a viewing scope, shown as an endoscope asillustrated at reference character 17, during a minimally invasiveprocedure such flexible endoscopic gastro-intestinal surgery. Theendoscope 17 preferably comprises an elongated flexible shaft portion 17a, though device 5 a may be used with rigid shaft viewing scopes, forexample, during laparoscopic surgery.

Endoscope 17 also comprises a proximal portion 17 b separated from adistal portion 17 c by shaft portion 17 a. Proximal portion 17 b ofendoscope 17 preferably comprises a control head portion 17 d. Controlhead portion 17 d preferably comprises a tissue treatment site viewer 17e and one or more directional control knobs 17 f and 17 g to control themovement of the flexible distal portion 17 c of flexible shaft 17 a.Control knob 17 f preferably comprises a right/left angulation controlknob while control knob 17 g preferably comprises an up/down angulationcontrol knob.

As shown in FIG. 8, flexible shaft 17 a houses at least one devicechannel 17 h through which surgical device 5 a may be passed. Also asshown, flexible shaft 17 a also preferably contains at least one viewingchannel 17 i to enable viewing through the distal portion 17 c. Flexibleshaft 17 a also preferably contains at least one fluid flow channel 17 jfor providing liquid (e.g. water) or gas (e.g. air) to a tissuetreatment site. Also preferably, electrosurgical device 5 a isconfigured to extend from the distal end portion 17 c, and morepreferably, the distal end surface 17 k of endoscope 17, as shown inFIG. 8.

As shown in FIGS. 11 and 12, electrosurgical device 5 a is preferablyassembled (e.g. mechanically connected via press-fit, mechanicalconnector, welded, adhesively bonded) adjacent the distal end 18 of along, hollow, tube 19 to preferably form a medical device assembly. Tube19 is preferably self-supporting and flexible, and more preferablycomprises a catheter which may be flexed to apply tamponade (e.g.compressive force) through the electrosurgical device 5 a to a bleedingsource in the gastrointestinal tract. Electrosurgical device 5 a, incombination with a catheter, may be referred to as a catheter assembly.

As best shown in FIGS. 10 and 12, electrosurgical device 5 a is alsopreferably electrically connected to the conductors 38 a, 38 b ofinsulated electrical wires 21 a, 21 b, respectively, which have beenpassed through lumen 23 of tube 19 as branches of cable 9 which isconnected to generator 6. However, in alternative embodiments, the tube19 may incorporate the conductors 38 a, 38 b of wires 21 a, 21 b in thetube wall (in essence creating a multi-lumen tube comprising threelumens where two of the lumens are occupied exclusively by theconductors 38 a, 38 b of wires 21 a, 21 b) to reduce the complexity ofitems being passed down lumen 23. Thereafter, electrosurgical device 5 aalong with the flexible tube 19 and wires 21 a, 21 b contained thereinmay enter channel entrance opening 17 l of device channel 17 h and arethereafter passed through and along at least a portion of the length ofdevice channel 17 h until exiting from channel exit opening 17 m.

As shown throughout FIGS. 9-16, and particularly FIGS. 12 and 15,electrosurgical device 5 a comprises a probe body 26. Probe body 26 ispreferably sized to pass from entrance 17 l to the exit 17 m of devicechannel 17 h of scope 17. Probe body 26 may comprise a solid,electrically non-conductive, insulative material impervious to the flowof fluid 24 therethrough including, but not limited to, ceramic orpolymer materials. Examples of non-conductive polymer materials include,but are not limited to, polyamide (a/k/a nylon), polyphthalamide (PPA),polyamideimide (PAI), polyetherimide (PEI), polyetheretherketone (PEEK),polyphenylenesulfide (PPS), polysulfone (PSO), polyethersulfone (PES),syndiotactic polystyrene (SPS), polyimide (PI) or any othernon-conductive polymer, thermoplastic or thermoset. Probe body 26 mayalso comprise a liquid crystal polymer and, more particularly, anaromatic liquid crystal polyester which is reinforced with glass fiber,such as Vectra® A130 from Ticona, 90 Morris Avenue, Summit, N.J.07901-3914. Where probe body 26 comprises a ceramic, it may comprise amachinable ceramic material such as sold under the tradename MACOR. Inother embodiments, the non-conductive material of the probe body 26 maybe coated with a non-conductive, lubricating or non-stick coating, suchas polytetrafluoroethylene (PTFE).

As shown throughout FIGS. 9-16, electrosurgical device 5 a is greatlyenlarged since, for example, in one exemplary embodiment thecross-sectional dimension of device 5 a, specifically its diameter, isabout 7 French (about 2.4 mm or 0.095 inches). In another embodiment,the cross-sectional dimension of electrosurgical device 5 a may be about10 French (about 3.2 mm or 0.126 inches). In still other embodiments,electrosurgical device 5 a may be configured with any cross-sectionaldimension suitable to pass through the working channel of a viewingscope or of a trocar (also known as a cannula) where such a device isrequired.

As shown in FIGS. 9-12, for interacting with tissue, electrosurgicaldevice 5 a and, in particular, probe body 26, preferably comprise agenerally cylindrical shape 32 with the distal end portion of theelectrosurgical device 5 a and probe body 26 preferably comprising agenerally domed, hemispherical shape 67, such as that of a semi-circle,which provides a smooth, blunt contour outer surface.

As best shown in FIG. 12, electrosurgical device 5 a preferablycomprises a fluid flow manifold 40 located within probe body 26.Manifold 40 preferably comprises a discrete, rectilinear, longitudinallydirected, central fluid flow passage 41, preferably located on-centerabout longitudinal axis 31 of electrosurgical device 5 a. For device 5a, central flow passage 41 preferably extends between proximal end 35and distal end 27 of electrosurgical device 5 a through probe body 26and has a central flow passage fluid entrance opening 42 locatedadjacent the proximal end 35 of probe body 26. As shown in FIG. 12,central flow passage 41 preferably extends into and is fluidly coupledwith lumen 23 of flexible tube 19.

As best shown in FIGS. 12, 15 and 16, manifold 40 preferably comprisesat least one discrete, rectilinear, lateral fluid flow passage 43 whichis fluidly coupled to central fluid flow passage 41. As shown,preferably manifold 40 comprises a plurality of discrete, rectilinear,lateral fluid flow passages 43 a, 43 b which are defined and spaced bothlongitudinally along and circumferentially around the probe body 26 andcentral fluid flow passage 41. More preferably the lateral fluid flowpassages 43 a, 43 b are defined and spaced from proximal end 35 ofelectrosurgical device 5 a through probe body 26 to the distal end 27 ofelectrosurgical device 5 a through probe body 26.

Also as best shown in FIGS. 15 and 16, for device 5 a lateral fluid flowpassages 43 a, 43 b preferably each have a cross-sectional dimension,more specifically diameter, and corresponding cross-sectional area, lessthan the portion of central fluid flow passage 41 from which fluid 24 isprovided. Also, as best shown in FIGS. 12, 15 and 16, the lateral fluidflow passages 43 a, 43 b which preferably extend through the cylindricalportion 32 of probe body 26 are preferably formed substantially at aright angle (e.g. within about 10 degrees of a right angle) to thecentral fluid flow passage 41, both longitudinally andcircumferentially. Also as shown in FIGS. 12, 15 and 16, the lateralfluid flow passages 43 a, 43 b are preferably formed substantially at aright angle to the outer tissue interacting/treating surfaces 28, 50 ofthe electrosurgical device 5 a.

Preferably, lateral fluid flow passages 43 a, 43 b extend from centralfluid flow passage 41 to lateral flow passage fluid exit openings 44 a,44 b located on surfaces of electrosurgical device 5 a configured forinteracting with and treating tissue. As shown in FIGS. 12, 15 and 16,lateral flow passage fluid exit openings 44 a, 44 b are located onexposed outer surface 28 of probe body 26, or an exposed outer surface50 of electrode 29 a-c, 30 a-c, which are discussed in greater detaillater in this specification. More preferably, lateral fluid flowpassages 43 a, 43 b preferably are configured to extend from centralfluid flow passage 41 to lateral flow passage fluid exit openings 44 a,44 b located on the outer surface 28 of probe body 26 and outer surface50 of electrodes 29 a-c, 30 a-c, respectively, such that lateral flowpassages 43 a, 43 b and associated fluid exit openings 44 a, 44 b aredefined and spaced both longitudinally along and circumferentiallyaround the outer surfaces 28 and 50 of electrosurgical device 5 a,preferably between proximal end 35 of electrosurgical device 5 a and thedistal end 27 of electrosurgical device 5 a and probe body 26.

As best shown in FIGS. 12, 15 and 16, central flow passage 41 may belined by a liner 45, preferably comprising a non-corrosive, impervious(to fluid 24), metal tube (e.g. stainless steel tubing) located within athrough bore 46 of probe body 26 which extends from proximal end 35 todistal end 27 of electrosurgical device 5 a and probe body 26. Also asbest shown in FIGS. 12, 15 and 16, preferably the outer wall surface ofliner 45 contacts the inner surface of bore 46 of probe body 26 anddiscrete lateral fluid flow passages 43 a, 43 b extend through the wallthereof. Alternatively, liner 45 may comprise a cylindrical coil springwith the lateral openings provided between the coils of the spring.

As best shown in FIG. 12, distal wall section 25 of liner 45 adjacentdistal end 27 of the electrosurgical device 5 a and probe body 26partially defines the distal end of the wide proximal portion 41 a ofthe central flow passage 41 (with the proximal end of the distal narrowportion 41 b of the central flow passage 41 defining the remainder ofthe distal end of the wide portion 41 a of the central flow passage 41in this embodiment). Distal wall section 25 of liner 45 also narrows thecentral flow passage 41 from wide portion 41 a to narrow portion 41 band defines a narrow central fluid passage exit opening 62. As shown, inthis manner, preferably, the distal portion of the central flow passage41 comprises a counterbore configuration. In other words, two adjacentcircular openings about the same axis, but of different diameter. Moreparticularly, wide portion 41 a and narrow portion 41 b of central flowpassage 41 preferably comprise the configuration of a counterboreadjacent the distal end 27 of electrosurgical device 5 a.

During use of electrosurgical device 5 a, the distal wall section 25inhibits fluid flow from wide portion 41 a through the narrow portion 41b of the central flow passage 41. In other words, distal wall 25inhibits fluid 24 from exiting from the central fluid passage exitopening 62 as compared to a situation where distal wall 25 would not beused and the central flow passage 41 only would consist of wide portion41 a. In the above manner, at least a portion of the distal end of thecentral flow passage 41 is defined by an occlusion (i.e. wall section25) formed by a portion of the electrosurgical device 5 a.

More preferably, wall section 25 substantially occludes and inhibitsfluid 24 from exiting from the central flow passage exit opening 62.Throughout this specification, occlusion of central flow passage 41 andthe corresponding inhibiting of flow from exiting from the central fluidpassage exit opening 62 of the central flow passage 41 can be consideredsubstantial when the occlusion and corresponding inhibiting of flowresults in increased flow from the lateral flow passages 43 a, 43 b. Inother words, the occlusion functions as a fluid flow diverter andredirects fluid coming in contact therewith from flowing parallel withthe longitudinal axis 31 of central flow passage 41 to flowing radiallyfrom the longitudinal axis 31 through lateral flow passages 43 a, 43 b.

As best shown in FIGS. 12, 15 and 16, preferably the probe body 26 hasan outer surface 52 on which at least a portion of one energy providingmember is located, overlies and is connected. As shown in FIGS. 9 and10, the energy providing member preferably comprises a pair ofelectrical conductors 29, 30 which are respectively electricallyconnected to insulated wires 21 a, 21 b which are ultimately connectedto generator 6. Conductors 29, 30 preferably comprise an electricallyconductive metal, which is preferably non-corrosive, such as stainlesssteel or titanium.

The conductors 29, 30 are preferably configured to provide energy totissue for hemostatic therapy and/or for tissue treatment of the wall ofan anatomical tube. Each conductor 29, 30 may be branched into, forexample, additional sub-conductors, such as comprising three elongatedlongitudinally directed strip electrodes 29 a, 29 b, 29 c and 30 a, 30b, 30 c which will provide energy to treat tissue. As shown, theelectrodes may be aligned generally parallel with the longitudinal axis31 on the peripheral surface of the probe body 26 (comprising exposedprobe body surfaces 28 and covered probe body surfaces 52) and arepreferably angularly uniformly distributed, in this embodiment atangular intervals of 60 degrees. The electrodes 29 a-c, 30 a-c ofconductors 29 and 30 are respectively successively spaced from eachother by gaps, G. In one embodiment, the gaps G are generally at leastabout twice the widths W of the electrodes at the cylindrical portion 32of the probe body 26. For a probe body 26 of a 2.4 mm diameter, the gapsG are about 0.8 mm and the widths W are about 0.4 mm. Generally, thewider the gap G between the electrodes the deeper the effect on tissuebeing treated.

Preferably, the electrodes 29 a-c, 30 a-c are provided alternatingelectrical current, so that the electrodes alternate polarity betweenpositive and negative charges, and adjacent electrodes comprisesopposite polarities at any given time to create an electrical field withcurrent flow from the positive to negative charge. In other words, forexample, preferably while electrodes 29 a-c comprise a first polarity(e.g. positive), electrodes 30 a-c comprise a second opposite polarity(e.g. negative). In the above manner, the plurality of uniformlydistributed opposite electrode pairs formed around the longitudinal axis31 create one or more bipolar electrical circuits, with the number ofelectrode poles generally equal to the number of circuits. For example,with the six electrode poles described above, an electrical array whichextends circumferentially around longitudinal axis 31 and device 5 acomprising six bipolar circuits is created between adjacent successivepoles as shown by electrical field lines 57 a-f in FIG. 13.

Conductors 29, 30, including electrodes 29 a-c, 30 a-c may comprisepreformed metal which is then placed on probe body 26, orformed-in-place metal which comprises a metallic compound which isformed-in-place on the probe body 26, typically via painting orspraying. In one particular embodiment, conductors 29, 30 and electrodes29 a-c, 30 a-c may be formed by first applying metal completely to theouter surfaces 28 and 52 of probe body 26 (such as by dip coating theouter surface in a liquid metal bath) then removing metal in excess ofthe conductors 29, 30 and electrodes 29 a-c, 30 a-c from the surface 28to define the conductors 29, 30 and electrodes 29 a-c, 30 a-c, such asby the use of a laser.

Also as shown in FIGS. 9 and 10, where elongated, longitudinallydirected electrodes are utilized (e.g. from the proximal end 35 to thedistal end 27 of the electrosurgical device 5 a and probe body 26), suchas with electrosurgical device 5 a, preferably at least three sets ofopposite electrode poles are provided. In this manner, at least bipolar,and frequently greater, polar tissue contact and electrocoagulation canbe achieved substantially independent of the orientation of the probebody 26 relative to the tissue treatment site. This is advantageous whenthe device 5 a is used through endoscope 17 so that front end use (e.g.domed portion 67), sideways use (e.g. cylindrical portion 32) or obliqueuse (e.g. combination of domed portion 67 and cylindrical portion 32) ofthe electrosurgical device 5 a results in at least a bipolar contactwith the tissue treatment site.

As best shown in FIGS. 10 and 14, electrodes 29 a-c of conductor 29 arepreferably electrically coupled to each other at the proximal end 35 ofthe probe body 26. Preferably, electrodes 29 a-c of conductor 29 areelectrically coupled via a conductor 29 which comprises an electricallyconductive radial band, preferably located on a radially recessedshoulder 34 of probe body 26 located at the proximal end 35 of probebody 26. The electrical coupling between electrodes 29 a-c and conductor29 is preferably made via radially displaced localized conductive tabs36 a-c. In turn, conductor 38 b of insulated wire 21 b is preferablyconnected to band preferably in a notch 37 formed in the band and inshoulder 34, where notch 37 is sized to receive conductor 38 b of wire21 b. Conductor 38 b of insulated wire 21 b is preferably connected to asurface 39 of notch 37 via an electrical connector comprising solder(e.g. silver) from soldering.

As best shown in FIGS. 9 and 12, electrodes 30 a-c of conductor 30 arepreferably electrically coupled to each other at the distal end 27 ofthe electrosurgical device 5 a and probe body 26. Preferably, electrodes30 a-c of conductor 30 are electrically coupled via a conductor 30comprising an electrically conductive hub preferably located at thedistal end 27 of the electrosurgical device 5 a and probe body 26. Awall section 47 of the conductor 30 overlying wall section 25 of liner45 may also function an occlusion which either partially defines thedistal portion of the central flow passage 41 (i.e. where central flowpassage 41 comprises a narrow portion 41 b and a central fluid passageexit opening 62) or completely defines the distal end of the centralflow passage 41 (i.e. where the central flow passage does not continuethrough the wall section 47 of conductor 30), particularly when liner 45is not occluded at its distal end (i.e. does not include wall section25).

Conductor 30 is preferably electrically coupled to hollow conductivemetal liner 45 to which, in turn, conductor 38 a of insulated wire 21 ais preferably connected to a surface of hollow metal liner 45 at theproximal end 35 of probe body 26 via an electrical connector comprisingsolder (e.g. silver) from soldering. Alternatively where, for example,liner 45 is not utilized, conductor 38 a of insulated wire 21 a may beconnected to an inner surface 49 of conductor 30.

As shown in FIGS. 9 and 16, preferably the plurality of lateral flowpassages 43 a which extend through probe body 26 to fluid exit openings44 a are defined and spaced along the outer surface 28 of probe body 26between at least one pair of adjacent electrodes. As shown, preferablythe plurality of lateral flow passage fluid exit openings 44 a areconfigured to form both longitudinal and circumferential straight rows,and are preferably uniformly spaced relative to one another. Also,preferably lateral flow passages 43 a are configured to distribute fluidflow exiting from fluid exit openings 44 a substantially uniformly.Lateral flow passages 43 a of this exemplary embodiment preferably havea cross-sectional dimension (e.g. diameter) in the range between andincluding about 0.1 mm to 2 mm and more preferably have a diameter inthe range between and including about 0.15 mm to 0.2 mm.

Also as shown in FIGS. 9 and 15, preferably the plurality of lateralflow passages 43 b which extend through probe body 26 and at least oneelectrode 29 a-c, 30 a-c to fluid exit openings 44 b are defined andspaced along the outer surface 50 of electrodes 29 a-c, 30 a-c. Asshown, preferably the plurality of lateral flow passage fluid exitopenings 44 b are configured to form both longitudinal andcircumferential straight rows, and are preferably uniformly spacedrelative to one another. Also, preferably lateral flow passages 43 b areconfigured to distribute fluid flow exiting from fluid exit openings 44b substantially uniformly. Lateral flow passages 44 b of this exemplaryembodiment preferably have a cross-sectional dimension (e.g. diameter)in the range between and including about 0.1 mm to 2 mm and morepreferably have a diameter in the range between and including about 0.15mm to 0.2 mm.

As best shown in FIG. 10, electrical device 5 a preferably furthercomprises a member 51 which comprises a gasket portion 51 a configuredto electrically insulate conductors 38 a, 38 b from one another andinhibit a short circuit (i.e. a low resistance, alternate path throughwhich current will flow, often resulting in damage, rather than throughthe load circuit) from forming between conductors of differentelectrical potential (e.g. conductors 29/38 b with conductors 30/38 a)in the presence of electrically conductive fluid, which would causeelectrical current to flow between conductors (e.g. 29/38 b and 30/38 a)prior to the current reaching electrodes 29 a-c and 30 a-c, thusbypassing or detouring away from the electrodes. Member 51 preferablycomprises an insulative flexible polymer material, such as an elastomerand, in this embodiment, preferably comprises the geometry of a thin,flat circular member, such as that of a washer. As shown in FIG. 10,gasket portion 51 a surrounds aperture 51 b through which wire 21 bextends. Thereafter, gasket portion 51 a preferably forms a gasket withthe insulator of wire 21 b to inhibits fluid 24 from lumen 23 of tube 19from contacting conductors 38 b and 29.

Member 51 also preferably includes a second gasket portion 51 c whichsurrounds aperture 51 d through which liner 45 extends and thereafterforms a gasket with the outer surface of liner 45 to also inhibit fluid24 from lumen 23 of tube 19 from contacting conductor 38 b or 29.

In other embodiments, electrical device 5 a may further comprise asensor, such as probe body 26 itself, for sensing, for example,temperature, pressure or saline impedance sensor for sensing the phasechange associated with the onset of boiling, or which may be located inor on probe body 26, adjacent an electrode and/or the tissue.

As best shown in FIGS. 12, 15 and 16, probe body 26 preferably comprisesa circular shape with a uniform diameter along the longitudinal lengthof the cylindrical portion 32. As best shown in FIGS. 15 and 16, theouter surface 50 of at least a portion of at least one of the electrodes29 a-c, 30 a-c is stepped up or otherwise protruding relative to anadjacent exposed outer surface 28 of the probe body 26 by the thicknessof the electrodes, preferably in a thickness range between and includingabout 0.01 mm to 2.0 mm and, more preferably, in the range between andincluding about 0.1 mm to 0.5 mm. As shown in FIGS. 15 and 16, the outersurface 50 of all of the electrodes 29 a-c, 30 a-c is stepped uprelative to an adjacent exposed outer surface 28 of the probe body 26 bythe thickness of the electrodes.

Another exemplary electrosurgical device of the present invention whichmay be used in conjunction with the system of the present invention isshown at reference character 5 b in FIG. 17, and more particularly inFIGS. 17-19. As best shown in FIG. 19, at least a portion of at leastone of the electrodes 29 a-c, 30 a-c is located in a recess such thatthe outer surface 50 of the electrodes is flush relative to an adjacentexposed outer surface 28 of the probe body 26. As shown in FIG. 19, allthe electrodes 29 a-c, 30 a-c are located in recesses 53 with the depthof the recesses 53 equal to the thickness of the electrodes such thatthe outer surface 50 of the electrodes 29 a-c, 30 a-c is flush relativeto an adjacent exposed outer surface 28 of the probe body 26. In thismanner, device 5 b may tend to move along the surface of the tissue moreeasily than 5 a as the surface roughness associated with protrudingelectrodes is eliminated.

Another exemplary electrosurgical device of the present invention whichmay be used in conjunction with the system of the present invention isshown at reference character 5 c in FIG. 20, and more particularly inFIGS. 20-22. As best shown in FIG. 22, recess 53 provides, at least inpart, at least one elongated fluid flow channel 54 for fluid 24. Also asshown in FIG. 22, preferably at least a portion of at least one of theelectrodes 29 a-c, 30 a-c is located in the recess 53, and preferablysuch that the outer surface 50 of the electrodes is stepped down orotherwise recessed relative to an adjacent exposed outer surface 28 ofthe probe body 26. As shown in FIG. 22, all the electrodes 29 a-c, 30a-c are located in recesses 53, with the depth of the recesses 53greater than the thickness of the electrodes such that the outer surface50 of the electrodes 29 a-c, 30 a-c is stepped down relative to anadjacent exposed outer surface 28 of the probe body 26. Also as shown inFIG. 22, the fluid flow channel 54 is preferably provided in the portionof the recess 53 overlying the outer surface 50 of the electrodes 29a-c, 30 a-c.

Preferably the configuration of the fluid flow channel 54 as provided bygeometry (e.g. width, depth), the material and/or surface treatment ofthe probe body 26, and/or the material and/or surface treatment of theelectrodes 29 a-c, 30 a-c, and may be arranged such that surface tensionwill act to retain fluid collected in the channel 54 where the force ofgravity is acting to remove the fluid from the channel 54. However,while it is desirable that a certain predetermined amount of surfacetension act to retain fluid collected in the channel 54 in the presenceof gravity, the surface tension must be balanced against the inhibitionof fluid flow from lateral flow passages 43 b. While partial inhibitionfrom lateral flow passages 43 b is acceptable, fluid flow channel 54should not be configured and arranged such that surface tension will actto completely inhibit or prevent fluid from flowing out of lateral flowpassages 43 b.

Among other things, fluid flow channel 54 provides a distributionconduit for distributing fluid contained therein, which has passedthrough lateral fluid flow passages 43 b from central flow passage 41,more uniformly on the outer surface 50 of the electrodes 29 a-c, 30 a-cas compared to the situation where fluid flow channel 54 is not used. Inother words, the use of fluid flow channel 54 will generally increasethe surface area 50 of the electrodes 29 a-c, 30 a-c covered with fluidfrom lateral fluid flow passages 43 b as compared to the situation wherefluid flow channel 54 is not used.

Among other things, fluid flow channel 54 also provides a distributionconduit for distributing fluid contained therein, which has passedthrough lateral fluid flow passages 43 b from central flow passage 41,more uniformly on the adjacent exposed outer surfaces 28 of the probebody 26 as compared to the situation where fluid flow channel 54 is notused. For example, the use of fluid flow channel 54 will generallyincrease the surface area 28 of the probe body 26 covered with fluidfrom lateral fluid flow passages 43 b as a result of fluid overflowingout of the channel 54 along the longitudinal length of the channel 54and flowing over the surface 28 of the probe body 26 as compared to thesituation where fluid flow channel 54 is not used.

In use, when tissue 20 overlies and occludes the opening 55 of fluidflow channel 54 for a portion of its longitudinal length, thusinhibiting fluid flow exiting therefrom, fluid from channel 54 may stillbe expelled from the electrosurgical device 5 c after flowinglongitudinally in the channel 54 to a remote location, typically atdistal end 27 of electrosurgical device 5 c and probe body 26, where thechannel 54 is unoccluded and uninhibited to fluid flow exitingtherefrom.

However, in certain instances, it may be possible that fluid flowchannel 54 may be occluded by tissue 20 completely along itslongitudinal length, thus completely inhibiting fluid flow from exitingthrough opening 55. In order to overcome this problem, at least aportion of probe body 26 may comprise a material pervious to the passageof fluid 24, therethrough, such as a porous material. As shown in FIG.23, in another embodiment of the electrosurgical device of the presentinvention, as shown at reference character 5 d in FIG. 23, the wall 56of channel 54, as well as exposed outer surface 28 of probe body 26 areporous and connected by a plurality of tortuous paths 59 in the porousmaterial. Consequently, rather than flowing out of channel 54 from adirect opening 55, which may be occluded by tissue 20, the fluid mayexit indirectly from the flow channel 54 by first flowing throughtortuous paths 59 of probe body 26 from side walls 56 of the channel andthen exit the probe body 26 from surface 28, which may be in unoccludedby tissue 20. Alternatively, if adjacent surface 28 of the probe body 26is also occluded by tissue 20, the fluid may continue to flow throughtortuous paths 59 of probe body 26 and exit the probe body 26 from asurface 48 of a remote flow channel 54 or surface 28, 50, which may bein unoccluded by tissue 20.

As also shown in FIG. 23, in addition to the probe body 26 comprising aporous material, at least one of the electrodes 29 a-c, 30 a-c may alsocomprise a porous material. Consequently, fluid flowing through thetortuous paths 59 of the probe body 26 may exit from surface 52 of theprobe body 26 covered by an electrode 29 a-c, 30 a-c, flow though thetortuous paths 60 of the electrode 29 a-c, 30 a-c and then exit fromouter surface 50 of the electrode 29 a-c, 30 a-c to provide similaradvantages as the porous probe body 26.

Where the probe body 26 and/or electrodes 29 a-c, 30 a-c comprise aporous material, the discrete, rectilinear lateral fluid flow passages43 a, 43 b may be either supplemented with or replaced by the pluralityof tortuous, interconnected passages 59 and/or 60 formed in the porousmaterial with a porous surface 28 and/or 50 to more evenly distributefluid flow and allow infusion of the conductive solution to the tissuetreatment site. Also alternatively, the lateral fluid flow passages 43a, 43 b may extend towards surfaces 28 and/or 50, but terminate prior tosurfaces 28 and/or 50 and not extend thereto, with passages 59 and/or 60in fluid communication with lateral flow passages 43 a, 43 b thereafterproviding fluid 24 to surfaces 28 and/or 50.

Where the probe body 26 comprises a porous non-electrically conductivematerial, the conductors 38 a, 38 b and corresponding electrodes 29 a-c,30 a-c, respectively, may still be further insulated from one another toreduce power losses associated with any short circuit which may developthrough the probe body 26 and, more particularly, through the conductivefluid flowing through the tortuous paths 59 of the probe body 26. Asshown also in FIG. 23, in order to further insulate the respective polesfrom one another, a water resistant or water proof coating 58 may belocated between surfaces of probe body 26 adjoining portions of theelectrical circuit (e.g. conductors 38 a, 38 b and electrodes 29 a-c, 30a-c), such as surface 33 of liner 45, surface 63 of lateral flow passage43, the surface if the central flow passage 41, the surface of bore 46of probe body 26 and/or notch surface 39.

With regards to porous electrodes 29 a-c, 30 a-c porous sintered metalis available in many materials (such as, for example, 316L stainlesssteel, titanium, Ni-Chrome) and shapes from companies such as Porvair,located in Henderson, N.C.

Porous metal components can be formed by a sintered metal powder processor by injection molding a two-part combination of metal and a materialthat can be burned off to form pores that connect (open cell) to eachother. With sintering, for example, typically solid particles ofmaterial are placed in a mold under heat and pressure such that theouter surface of the particles soften and bond to one another with thepores comprising the interstices between the particles. Alternatively,when porosity is formed by burning off material, it is not theinterstice between the particles which provides the porosity as withsintering, but rather a partial evisceration of the material generallyprovided by the removal of a component with a lower melt temperaturethan the burn off temperature.

With regards to a non-electrically conductive porous probe body 26,porous polymers and ceramics can be used to replace non-porous polymersand ceramics, respectively. Suitable polymer materials include hightemperature open cell silicone foam and porous polycarbonates, amongothers. Different from sintering or evisceration of material, formationof porosity in open cell polymer foams is typically accomplished by theintroduction of gas bubbles, either chemically or physically, into thepolymer during its formation or melt phase which form a cellularstructure. However, sintering or evisceration of material may also beused with polymer materials. While the porous polymers themselves aregenerally non-conductive, they may also be used to conduct the RF energythrough the porous polymer thickness and surface to the tissue to betreated by virtue of conductive fluid contained within the plurality ofinterconnected tortuous passages.

Porous ceramics also generally fall into the category of beingnon-conductive, since they could distribute conductive fluid flow,withstand high temperatures and be machinable or moldable formanufacturing purposes. Preferably, the material used transmits bothfluid flow and electrical energy; thus, materials with propertiesbetween high-electrical conductivity metals and low electricalconductivity polymers are also contemplated, such as porouscarbon-filled polymers. In these embodiments, conductive fluid flow isdistributed along the length of the electrodes, where porous material isused to fabricate the electrodes. All or a portion of the electrodes canbe porous according to the invention.

Preferably the tortuous passages 59 and 60 in the porous materials havea pore size (cross-sectional dimension) in the range between andincluding about 2.5 micrometers (0.0025 mm) to 500 micrometers (0.5 mm)and more preferably has pore size in the range between and includingabout 10 micrometers (0.01 mm) to 120 micrometers (0.12 mm). Even morepreferably, the porous material has a pore size in the range between andincluding about 20 micrometers (0.02 mm) to 80 micrometers (0.08 mm).

In addition to providing a more uniform distribution of fluid exitingfrom channel 54, the porous materials also provides other advantages.For example, lateral fluid flow passages 43 a, 43 b are difficult tomold or machine below a size of 0.276 millimeters (0.007 inches).Conversely, the porous material may provide passages of a smallerdimension. Furthermore, in addition to providing smaller fluid passages,when the probe surface 28 and/or electrode surface 50 in contact withtissue 20 are porous and dissipate fluid, tissue 20 is less apt to stickto the surfaces 28 and/or 50 as compared to the situation where thesurfaces 28 and/or 50 are not porous. In addition, by providing fluid tosurfaces 28 through tortuous paths 59, heated and/or electrified fluidcan now be provided more uniformly to surface 28, which results in awider tissue treatment region as compared to when the surfaces 28 is notporous.

Preferably the porous material provides for the wicking (i.e. drawing inof fluid by capillary action or capillarity) of the fluid into the poresof the porous material. In order to promote wicking of the fluid intothe pores of the porous material, preferably the porous material alsocomprises a hydrophilic material, which may be provided, for example, bythe porous material itself with or without post treating (e.g. plasmasurface treatment such as hypercleaning, etching or micro-roughening,plasma surface modification of the molecular structure, surface chemicalactivation or crosslinking), or by a coating provided thereto, such as asurfactant.

As shown in embodiments 5 c and 5 d, and more specifically in FIGS. 22and 23, recess 53 comprises a rectangular cross section formed in partby a first side wall, a second opposing side wall and a bottom wall.Furthermore, electrodes 29 a-c, 30 a-c also comprise a rectangularcross-sections, and lateral flow passages 43 b extend through theelectrodes. However, in other embodiments of the invention, recess 53and electrodes 29 a-c, 30 a-c may comprises features and cross-sectionalshapes other than that of a rectangle. These various electrosurgicaldevices are discussed particularly in embodiments 5 e-5 h in thefollowing paragraphs. Discussion of embodiments 5 e-5 h focuses on oneparticular electrode of the group 29 a-c, 30 a-c, recess 53, flowchannel 54 and lateral flow passage 43, as the case may be. However, itshould be understood that the features discussed for each embodiment 5e-5 h may equally apply to all the electrodes of the group 29 a-c, 30a-c, recesses 53, flow channels 54 and lateral flow passages 43 of therespective embodiment.

In an alternative embodiment, rather than an occlusion formed by aportion of the electrosurgical device 5 a defining at least a portion ofthe distal end of the central flow passage 41, an occlusion maycompletely define the distal end of the central flow passage 41. Asshown in FIG. 24, for device 5 e distal wall section 25 of liner 45completely defines the end of the central flow passage 41. In otherwords, central flow passage 41 only comprises wide portion 41 a and doesnot comprise narrow portion 41 b or a central fluid passage exit opening62. In this manner, the distal end of the central flow passage 41comprises a blind end. In other words, the central flow passage 41 doesnot continue through electrosurgical device 5 e. The distal end of thecentral flow passage terminates within the confines of theelectrosurgical device 5 e and is closed by a portion of theelectrosurgical device structure, in this embodiment wall section 25 ofliner 45, forming the distal end of the central flow passage 41.

As shown in FIG. 25, electrode 30 a of electrosurgical device 5 fcomprises a circular cross-sectional shape, preferably with a constantdiameter. More particularly, preferably wire conductor 38 a of wire 21 acomprises electrode 30 a. In this manner, conductor 38 a and electrode30 a comprise a unitarily formed piece which reduces complexity. In thisembodiment, it should be understood that the thickness of the electrodeis equal to the width of the electrode, with both equal to the diameterof the electrode. Furthermore, electrosurgical device 5 f comprises anumber of important distinctions from embodiments 5 a-5 e disclosedthusfar.

As shown in FIG. 25, lateral flow passage 43 does not extend throughelectrode 30 a, and does not have to extend through electrode 30 abefore having fluid communication with fluid flow channel 54, whichreduces complexity. As shown, lateral flow passage 43 is locateddirectly beneath fluid flow channel 54, rather than having electrode 30c in between. Also as shown, lateral flow passage 43 is at leastpartially located beneath overlying electrode 30 c with a portion offluid flow channel 54 located in between.

Also as shown in FIG. 25, in addition to a portion of fluid flow channel54 overlying a portion of the electrode 30 a in recess 53, at least aportion of fluid flow channel 54 underlies a portion of the electrode 30a and at least a portion of fluid flow channel 54 is located on at leastone longitudinal side of a portion of the electrode 30 a in recess 53.More particularly, as shown in FIG. 25, a portion of fluid flow channel54 is located on two longitudinal sides of the electrode 30 a in recess53. Thus, with the configuration of electrosurgical device 5 f, fluidflow channel 54 is not limited to only overlying electrode 30 a, butrather can take on a number of different localities within recess 53,depending on the application.

As shown in FIG. 26, electrode 30 a of electrosurgical device 5 g alsocomprises a circular cross-sectional shape, preferably with a constantdiameter. Similar to electrosurgical device 5 f, preferably wireconductor 38 a of wire 21 a also comprises electrode 30 a. However, incontrast to electrosurgical device 5 f, lateral flow passage 43 ofdevice 5 g extends through electrode 30 a. In order to better facilitatethe formation of lateral flow passage 43 through electrode 30 a,preferably recess 53 is configured to receive and properly seatelectrode 30 a therein substantially without any side-to-side movementand prior to the formation of lateral flow passage 43. As shown, theseat for electrode 30 a in recess 53 comprises a semi-circle ofsubstantially the same width, more specifically diameter, as that ofelectrode 30 a. Preferably electrode 30 a is first seated in recess 53without lateral flow passage 43 formed therein, then, once seated,lateral flow passage 43 is formed through electrode 30 a and probe body26 and liner 45 simultaneously. In a preferred embodiment, lateral flowpassage 43 is formed by a laser acting directed at the outer surface ofthe electrode 30 a.

As shown in FIG. 27, electrode 30 a and recess 53 of electrosurgicaldevice 5 h comprises a semi-circular cross-sectional shape and no fluidflow channel 54 is present. However, the seating of electrode 30 a andthe formation of lateral flow passage 43 is preformed similarly to thatdisclosed for electrosurgical device 5 g.

As shown in FIG. 28, electrode 30 a and recess 53 of electrosurgicaldevice 5 i comprises a triangular cross-sectional shape and, similar toelectrosurgical device 5 h, no fluid flow channel 54 is present.However, as with electrosurgical device 5 h, the seating of electrode 30a and the formation of lateral flow passage 43 is preformed similarly tothat disclosed for electrosurgical device 5 g. In other words, theseating portion of recess 53 comprises substantially the same size andshape as the seating portion of the electrode 30 a.

Another exemplary electrosurgical device of the present invention whichmay be used in conjunction with the system of the present invention isshown at reference character 5 j in FIG. 29, and more particularly inFIGS. 29-31. As best shown in FIG. 30, rather than an occlusioncomprising wall section 25 of a liner 45 or a wall section 47 ofconductor 30 defining at least a portion of the distal end of thecentral flow passage 41 as with earlier embodiments, the occlusiondefining at least a portion of the distal end of the central flowpassage 41 may comprise a wall section 77 of a separately formed plug61.

As shown in FIG. 30, wall section 77 of plug 61 adjacent distal end 27of the electrosurgical device 5 j and probe body 26 partially definesthe distal end of the wide proximal portion 41 a of the central flowpassage 41 (with the proximal end of the distal narrow portion 41 b ofthe central flow passage 41 defining the remainder of the distal end ofthe wide portion 41 a of the central flow passage 41 in thisembodiment). Wall section 77 of plug 61 also narrows the central flowpassage 41 from wide portion 41 a to narrow portion 41 b and defines anarrow central fluid passage exit opening 62. In the above manner, thewall section 77 inhibits fluid flow from wide portion 41 a through thenarrow portion 41 b of the central flow passage 41. In other words, wallsection 77 inhibits the amount of fluid 24 exiting from the centralfluid passage exit opening 62 as compared to a situation where wallsection 77 would not be used and the central flow passage 41 only wouldconsist of wide portion 41 a. In the above manner, at least a portion ofthe distal end of the central flow passage 41 is defined by an occlusion(i.e. wall section 77) formed by a portion of the electrosurgical device5 j.

As best shown in FIG. 30, plug 61 may occlude the distal portion of theliner 45 adjacent distal end 27 of the electrosurgical device 5 j andprobe body 26 by being at least partially contained within the liner 45at the distal end 27 of the electrosurgical device 5 j and probe body26. Plug 61 may be fixed relative to probe body 26 and within liner 45as a result of being mechanically connected, preferably interference fit(e.g. with compression of the plug 61) or otherwise fastened (e.g.adhesively bonded) against the wall surface 33 of the liner 45. Plug 61preferably comprises an insulative deformable polymer material, such asa flexible elastomer and, in this embodiment, preferably comprises thegeometry of a thin, flat, circular member.

As shown in FIG. 30, where central flow passage 41 continues throughplug 61 and comprises narrowed portion 41 b, narrowed portion 41 b mayalso be configured for the passage an instrument 64 configured to treattissue (e.g. injection needle, biopsy forceps, polypectomy snare).Preferably, in its nonuse or retracted position, as shown in FIG. 30,instrument 64 is contained within the wide portion 41 a of the centralflow passage 41 within probe body 26 and thereafter, with use, theinstrument 64 is extended from the distal end 27 of the electrosurgicaldevice 5 j and probe body 26 when the instrument 64 is extendeddistally. The instrument 64 (shown as a hollow needle with an open,pointed tip) may be configured to penetrate tissue and enable injectiontherapy to tissue, such as the administration of a vasoconstrictor.sclerotic or topical anesthetic through the lumen of a needle.

Where instrument 64 comprises a hollow needle, preferably the needleextends proximally in the lumen of tube 45 and the lumen 23 of tube 19,towards the proximal end of tube 19 and exits the tube 19 through thesidewall thereof prior to the proximal end where it is then attached toan actuator assembly. Other instruments, such as the biopsy forceps, maybe configured to retrieve tissue samples, such as for biopsy.

Referring to FIGS. 32 and 33, in order for instrument 64 to passdistally through the narrow portion 41 b of central flow passage 41,depending on the relative size of the instrument 64 to the narrowportion 41 b of central flow passage 41, wall section 77 plug 61 may beconfigured to deform to facilitate penetration of the plug 61 by theinstrument 64 and, as a result, narrow portion 41 b of central flowpassage 41 may be configured to correspondingly increase itscross-sectional size of the through increasing diameter from a firstcross-sectional area to a second cross-sectional-area. Furthermore, inorder to inhibit the loss of fluid 24 through a narrow portion 41 b ofcentral flow passage 41 of increased size, a surface of the wall section77 of the plug 61 may be configured to correspondingly at leastpartially seal narrow portion 41 b and central fluid passage exitopening 62 against the outer wall surface of the instrument 64.

Conversely, once the instrument 64 is retracted proximally from plug 61,wall section 77 of plug 61 may be configured to return substantially toits pre-deformation configuration, and with the cross-sectional size ofthe narrow portion 41 b of the central flow passage 41 returningsubstantially to its pre-deformation cross-sectional size.

Another exemplary electrosurgical device of the present invention whichmay be used in conjunction with the system of the present invention isshown at reference character 5 k in FIG. 34, and more particularly inFIGS. 34-36. As best shown in FIG. 32, similar to embodiment 5 j, ratherthan an occlusion comprising wall section 25 of a liner 45 or a wallsection 47 of conductor 30 defining at least a portion of the distal endof the central flow passage 41 as with earlier embodiments, theocclusion defining at least a portion of the distal end of the centralflow passage 41 may comprise a wall section 77 of a separately formedplug 61.

In contrast to embodiment 5 j, rather than an occlusion formed by aportion of the electrosurgical device 5 k defining at least a portion ofthe distal end of the central flow passage 41, an occlusion maycompletely define the distal end of the central flow passage 41. Asshown in FIG. 32, wall section 77 of plug 61 completely defines the endof the central flow passage 41. In other words, central flow passage 41only comprises wide portion 41 a and does not comprise narrow portion 41b or a central fluid passage exit opening 62. In this manner, thecentral flow passage 41 is completely closed by a portion of theelectrosurgical device structure forming the distal end of the centralflow passage 41.

However, where central flow passage 41 does not continue through plug 61as a pre-formed opening, an opening comprising narrow portion 41 b and acentral fluid passage exit opening 62 may be configured to be formed inplug 61 by the instrument 64 during extension of the instrument 64through the plug 61. For example, plug 61 may be configured to bepenetrated (e.g. pierced) by the instrument 64 when the instrument 64extends distally to form an opening therein for the instrument 64 toextend and retract therethrough. Where the plug 61 is configured to bepenetrated, the specific area of the plug 61 configured for penetrationmay include an area of mechanical weakness, such as an area of reducedthickness 65, to promote tearing and opening in a predetermined area. Asshown, the area of reduced thickness 65 comprises a convex shaped recessformed in the proximal side of the plug 61.

Among other things, the configuration of electosurgical devices 5 j and5 k provide that the devices may be used either simultaneously orindependently with instrument 64. For example, once instrument 64, suchas a hollow hypodermic needle with an open, pointed tip, penetrates plug61 and extends distally from the distal end 27 of the electrosurgicaldevices 5 j or 5 k, as indicated above, a surface of the opening in theplug 61 penetrated by the needle, either formed prior or simultaneouslywith the use of the instrument 64, preferably seals against theperimeter outer wall surface of the needle to provide a gasket. At thistime, electrical power and fluid used with electrosurgical devices 5 jand 5 k from lumen 23 of tube 19 and central and lateral fluid flowpassages 41, 43 may be provided simultaneously to tissue with fluid fromthe lumen of instrument 64 (e.g. therapeutic hypodermic medication).Alternatively, when using the two functions independently, theelectrical power to electrosurgical devices 5 j and 5 k, or both theelectrical power and the conductive fluid to electrosurgical devices 5 jand 5 k, may be switched off when medication from instrument 64 isadministered.

In addition, among other things, instrument 64 can function as anelectrode extended distally from probe body 26. Where instrument 64comprises an electrode, preferably the electrode comprises the samealternating electrical charge as electrodes 30 a-c connected toconductor 30. An electrode which extends distally from probe body 26,such as instrument 64 is particularly useful to aid in treating tissuelocated distally end-on or oblique relative to probe body 26.

When instrument 64 comprises an electrode of the same alternatingelectrical charge as electrodes 30 a-c connected to conductor 30, inaddition to the electrical array which extends radially aroundlongitudinal axis 31 between adjacent successive poles, an electricalarray extends longitudinally between the instrument 64 comprising anelectrode and electrodes 29 a-c.

In other embodiments of the present invention, the instrument 64comprising an electrode may alternatively be used in a monopolarconfiguration (without electrodes 29 a-c, 30 a-c) with the secondelectrode located on the patient being treated. In this embodiment, oneof the wires going to the bipolar device would instead go to a groundpad dispersive electrode located on the patient's back or other suitableanatomical location.

Another exemplary electrosurgical device of the present invention whichmay be used in conjunction with the system of the present invention isshown at reference character 51 in FIG. 37, and more particularly inFIGS. 37-40. As best shown in FIG. 39, rather than an occlusioncomprising wall section 25 of liner 45, or a wall section 47 ofconductor 30 or a wall section 77 of plug 61 defining at least a portionof the distal end of the central flow passage 41 as with earlierembodiments, the occlusion defining at least a portion of the distal endof the central flow passage 41 may comprise a wall section 22 of theprobe body 26. Also as shown in FIG. 36, liner 45 has been eliminated.

As shown in FIG. 39, distal wall section 22 of probe body 26 adjacentdistal end 27 of the electrosurgical device 5 k partially defines thedistal end of the wide proximal portion 41 a of the central flow passage41. Distal wall section 22 of probe body 26 also narrows the centralflow passage 41 from wide portion 41 a to narrow portion 41 b anddefines a narrow central fluid passage exit opening 62. In the abovemanner, the distal wall section 22 inhibits fluid flow from wide portion41 a through the narrow portion 41 b of the central flow passage 41. Inother words, distal wall 22 inhibits the amount of fluid 24 exiting fromthe central fluid passage exit opening 62 as compared to a situationwhere distal wall 22 would not be used and the central flow passage 41only would consist of wide portion 41 a. In the above manner, at least aportion of the distal end of the central flow passage 41 is defined byan occlusion (i.e. wall section 22) formed by a portion of theelectrosurgical device 51.

Similar to embodiments 5 j and 5 k, electrosurgical device 51 may beconfigured to receive and instrument 64 therein. As with embodiments 5 jand 5 k, instrument 64 may comprise a hollow hypodermic needle with anopen, pointed tip, may be configured to treat tissue when extendeddistally from the distal end 27 of the electrosurgical device 51 andprobe body 26. More specifically, the instrument 64 may be configured topenetrate tissue and provide injection therapy to tissue.

Also similar to embodiments 5 j and 5 k, instrument 64 is configured topass distally through the narrow portion 41 b of central flow passage 41of device 51. Furthermore, similar to embodiment 5 j, narrow portion 41b and central fluid passage exit opening 62 of device 51 is formed priorto the use of the instrument 64. However, unlike embodiments 5 j and 5k, where a surface of narrow portion 41 b of central flow passage 41formed by wall section 77 of plug 61 preferably seals against the outerwall surface of the instrument 64, a surface of wall section 22 of probe26 of device 51 does not seal against the outer side wall surface 66 ofportion 94 of instrument 64. In this manner, fluid 24 may still exitfrom central fluid passage exit opening 62 during the use of instrument64.

In order to enable the distal tissue treatment portion 94 of instrument64 to pass through narrowed portion 41 b of central flow passage 41located at the distal end 27 of device 51, lateral narrow portion 41 bof this exemplary embodiment preferably has a cross-sectional dimension(e.g. diameter) in the range between and including about 0.1 mm to 2 mm(to accommodate hypodermic needles in the range of 12 to 36 gauge) andmore preferably has a diameter in the range between and including about0.45 mm to 0.51 mm (to accommodate a hypodermic needle of 25 gauge).

Also similar to previous embodiments, the central flow passage 41 ofdevice 51 is at least partially occluded distally by an occlusion. Inother words, for example, in earlier embodiments the central flowpassage 41 is at least partially occluded distally by wall section 25 ofliner 45, wall section 77 of plug 61 or wall section 22 of probe body26, with all three wall sections 25, 77 and 22 comprise a portion oftheir respective electrosurgical devices, Furthermore, all three wallsections form at least a portion of and define at least a portion of thedistal end of the central flow passage 41.

Also similar to embodiments 5 j and 5 k, the narrow portion 41 b of thecentral flow passage 41 of device 51 is occluded by an occlusionprovided by a portion 94 of a separate instrument 64. However, asdiscussed above, for device 51, preferably fluid 24 may still exit fromcentral fluid passage exit opening 62 during the use of instrument 64while for devices 5 i and 5 j preferably it does not.

However, in distinct contrast from embodiments 5 j and 5 k, fluid 24 maybe provided to device 51 from means other than lumen 23 of tube 19.Where instrument 64 comprises a hypodermic needle, preferably theelectrosurgical function of device 51 is used independently of thefunction of instrument 64. With use, after instrument 64 hasadministered treated tissue, and its presence is no longer required,instrument 64 may be removed from the central flow passage 41 ofelectrosurgical device 51 by being withdrawn from electrosurgical device51 proximally through lumen 23 of tube 19.

After withdrawing instrument 64 from electrosurgical device 51, narrowedportion 41 b of central flow passage 41 located at the distal end 27 ofthe device 51 may then be at least partially occluded by the distalportion 88 of a second instrument 73 inserted into electrosurgicaldevice 51 through lumen 23 of tube 19. As shown in FIG. 40, secondinstrument 73 also comprises a hollow tube with a lumen therein.

Continuing with FIG. 40, preferably the distal portion of wide portion41 a comprises a narrowing transition portion over the length of whichthe cross-sectional dimension and area of the central flow channel 41decreases from that of the wide portion 41 a to that of narrow portion41 b. As shown, the diameter and corresponding cross-sectional area ofwide portion 41 a of central fluid flow passage 41 narrows to thediameter and corresponding cross-sectional area of narrowed portion 41 bover the length of tapered portion 79 which, more particularly comprisesa tapered concave conical surface 75. Returning to second instrument 73,the distal portion 88 preferably comprises at least one fluid flowrestriction portion which is configured to occlude narrowed portion 41 bof central flow passage 41 when second instrument 73 is used inconjunction with electrosurgical device 51, particularly probe body 26.

More particularly, as shown in FIG. 40, distal portion 88 of secondinstrument 73 comprises a fluid flow restriction portion 81 which, moreparticularly comprises a tapered convex conical surface 69. Wheninstrument 73 is positioned for use, the surface 69 of tapered portion81 of instrument 73 cooperates with the surface 75 of tapered portion 79of probe body 26, preferably via at least partial contact, to at leastpartially occlude flow therebetween and the corresponding inhibit flowfrom central flow passage exit opening 62.

In addition to first flow restriction portion 81, the distal portion 88of second instrument 73 preferably further comprises a second flowrestriction portion 83 extending distally from fluid flow restrictionportion 81 and configured to extend into narrowed portion 41 b ofcentral flow passage 41. As shown second flow restriction portion 83comprises a cylindrical portion configured to restrict fluid flowthrough narrowed portion 41 b when the outer surface 84 of the secondflow restriction portion 83 cooperates, preferably via at least partialcontact, with the wall surface 85 of narrowed portion 41 b to at leastpartially occlude flow therebetween and the corresponding inhibit flowfrom central flow passage exit opening 62.

The distal portion 88 of second instrument 73 also preferably comprisesa guide portion 86 which extends distally from second flow restrictionportion 83. Guide portion 86 is preferably configured to guide thedistal portion 88 of the second instrument 73 into the wide portion 41 aof the central flow passage 41, but more particularly configured toguide the distal portion 88 of the second instrument 73 into narrowedportion 41 b of the central flow passage 41. In addition, upon enteringnarrowed portion 41 b, guide portion 86 is configured to positiontapered portion 81 of second instrument 73 with tapered portion 79 ofprobe body 26 of electrosurgical device 17 e in juxtaposed orientationrelative to one another. As shown, preferably surface 69 of taperedportion 81 of second instrument 73 and surface 75 tapered portion 79 ofprobe body 26 comprise non-parallel surfaces such that the two surfaces,when in contact, contact and seal on a point.

As shown, guide portion 86 preferably comprises a generally cylindricalshape with the distal end 87 of the guide portion 86 preferably having asmooth, blunt contour surface, and preferably comprising a generallydomed, hemispherical shape such as that of a semi-circle.

In addition to second instrument 73 comprising a guide portion 86, thetapered concave conical surface 75 of taper portion 79 of the probe body26 also functions as a guide portion when it cooperates with guideportion 86 of second instrument 73 to guide the distal portion 88 of thesecond instrument 73 from the wide portion 41 a of the central flowpassage 41 into the narrowed portion 41 b of central flow passage 41.

As shown in FIG. 40, in addition to the distal end 88 of the secondinstrument 73 preferably being occluded and providing for occludingnarrowed portion 41 b as outlined above, second instrument 73 alsopreferably comprises at least one fluid outlet passage 95 through theside wall 89 thereof. As shown, second instrument 73 comprises aplurality of fluid outlet passages 95 configured to provide fluid 24 tocentral flow passage 41 from lumen 71 of second instrument 73.

In order to inhibit the loss of fluid from central flow passage 41 tothe lumen 23 of tube 19, preferably the proximal end of the central flowpassage 41 of electrosurgical device 51 is also occluded such thatcentral flow passage 41 preferably comprises a chamber. As shown in FIG.40, the outer side wall surface 92 of the second instrument 73cooperates, preferably via at least partial contact, with the sidewallsurface portion 51 e of member 51 to at least partially occlude flow andprovide a seal therebetween and corresponding inhibit flow from centralflow passage 41 back into lumen 23 of tube 19. More particularly, asshown in FIG. 40, gasket portion 51 c which surrounds aperture 51 dthrough which second instrument 73 extends to preferably form a gasketwith the outer sidewall surface 92.

In order to guide instrument 64 or instrument 73 from the lumen 23 oftube 19 into central flow passage 41, preferably member 51 comprises atapered portion 51 f which, more particularly comprises a taperedconcave conical surface. Tapered portion 51 f of member 51 particularlycooperates with guide portion 86 of second instrument 73 to guide thedistal portion 88 of the second instrument 73 from the lumen 23 of tube19 into the wide portion 41 a of central flow passage 41.

In still other embodiments, the cross-sectional dimension (e.g.diameter) of the lumen 23 of tube 19 may be less than or equal to thecross-section dimension of the entrance opening to central flow passage41 thus eliminating the need for tapered portion 51 f.

In order to increase the uniformity of flow from central flow passage 41to all the lateral fluid flow passages 43, preferably central flowpassage 41 fills at least partially, and more preferably completely,with fluid 24 prior to expelling fluid 24 to the lateral fluid flowpassages 43. Consequently, it may be desirable to inhibit fluid exitingfluid outlet passages 95 from entering any lateral fluid flow passages43 directly as a result of the fluid exit openings 90 of fluid outletpassages 95 being aligned with the fluid entrance openings 91 of lateralfluid flow passages 43. Preferably when second instrument 73 ispositioned for use, preferably the fluid exit openings 90 of fluidoutlet passages 95 are at least partially offset (i.e. do not perfectlyunderlie) from the fluid entrance openings 91 of lateral fluid flowpassages 43 such that at least a portion of the fluid provided fromfluid outlet passages 95 must flow longitudinally prior to enteringlateral fluid flow passages 43.

In the absence of liner 45 to conduct electricity to electrodes 30 a-c,preferably electric connection between conductor 38 a of wire 21 a andelectrodes 30 a-c is preferably made via a conductor 93 which comprisesa longitudinally directed portion 96 and a laterally directed portion 97located with connected blind holes 98 and 99, respectively. Conductor 93preferably comprises a wire conductor and is preferably connected at itsproximal end to conductor 38 a of wire 21 a and at its distal end to oneof the electrodes 30 a-c joined by conductor 30.

In other embodiments of the invention, the electrosurgical device maycomprise less or more than six electrodes. For example, as shown inFIGS. 41-43, for electrosurgical device 5 m the conductors 29, 30 arepreferably branched into sub-conductors with each comprising twoelongated longitudinally directed strip electrodes 29 a, 29 b, and 30 a,30 b, which will provide energy to treat tissue. As shown in FIGS.41-42, the electrodes are preferably aligned generally parallel with thelongitudinal axis 31 on the peripheral surface of the probe body 26(comprising exposed probe body surfaces 28 and covered probe bodysurfaces 52) and are preferably angularly uniformly distributed, in thisembodiment at angular intervals of 90 degrees.

In another embodiment of the invention as shown in FIGS. 44-47, forelectrosurgical device 5 n the conductors 29, 30 are not branched intoan additional number of sub-conductors to provide energy to treattissue, but rather the strip electrodes 29 a, 29 b are circumferentiallydirected and extend around the perimeter of the probe body 26 in aspiral configuration. In other words, as the circumferentially directedelectrodes for device 5 n extend around the perimeter of the probe body26 they also simultaneously advance longitudinally on the probe body 26.Also as shown in FIG. 46, liner 45 has been eliminated, as well asnarrow portion 41 b of central flow passage 41 and central flow passageexit opening 62.

In another embodiment of the invention as shown in FIGS. 48-50, similarto embodiment 5 n, for electrosurgical device 5 o the conductors 29, 30are not branched into an additional number of sub-conductors to provideenergy to treat tissue. However, rather the strip electrodes 29 a, 29 bcircumferentially directed and extending around the circumference of theprobe body 26 in a spiral configuration, electrodes 29 a, 29 b ofembodiment 5 o are circumferentially directed and extending around theperimeter of the probe body 26 in a closed circular hoop configuration.In other words, as the circumferentially directed electrodes for device5 o extend around the perimeter of the probe body 26 they do not advancelongitudinally on the probe body 26.

In another embodiment of the invention as shown for device 5 p in FIGS.51-53, the electrode configuration comprises a combination oflongitudinally directed electrodes and circumferentially directedelectrodes. Furthermore, section 25 has been eliminated from liner 45.

As shown in FIGS. 51-53, longitudinally directed electrodes 29 a, 30 aare used in combination with circumferentially directed electrodes 29d-29 g and 30 d-30 g, respectively. More particularly electrodes 29 d-29g and 30 d-30 g comprise a partial or open circular hoop configuration.As shown each circular hoop configuration comprises a circular lengthcorresponding to about 140 degrees around longitudinal axis 31. However,the circular hoop configuration may comprise a circular lengthcorresponding to about 10 degrees to 170 degrees around longitudinalaxis 31. Preferably the circular hoop configuration comprise a circularlength corresponding to at least 80 degrees around longitudinal axis 31.Also as shown, electrodes 29 d-29 g and 30 d-30 g extend from electrodes29 a, 29 b at substantially at right angle and on the outer tissueinteracting surfaces 28 of the electrosurgical device 5 p and terminateprior to intersection with the opposite longitudinally directedelectrode.

Also as shown, preferably the circumferentially directed electrodesextend circumferentially around the probe body 26 from both opposinglongitudinal sides of a longitudinally directed electrode. Furthermore,preferably the circumferentially directed electrodes on each side of thelongitudinally directed electrode are aligned along the longitudinallength of the longitudinal electrode. For example, electrodes 30 d and30 e extend circumferentially around the probe body 26 from bothopposing longitudinal sides of a longitudinally directed electrode 30 a.Furthermore, electrodes 30 d and 30 e are aligned along the longitudinallength of longitudinal electrode 30 a.

In the above manner, preferably a single circular hoop configurationcomprising a circular length double to the circular length of electrodes30 d and 30 e individually is formed. In other words, the circularlength of electrodes 30 d and 30 e combined corresponds to about 300degrees around longitudinal axis 31 is formed. However, circular hoopconfiguration may comprise a circular length corresponding to about 20degrees to 340 degrees around longitudinal axis 31. Preferably thecircular hoop configuration comprise a circular length corresponding toat least 160 degrees around longitudinal axis 31.

In contrast to the earlier disclosed embodiments, as shown in FIG. 54,electrosurgical device 5 q is connected adjacent the distal end 18 of arigid, self-supporting, hollow tube 19 (as opposed to the flexible tubeof earlier disclosed embodiments) which form a shaft. Device 5 q maycomprise any of the electrosurgical devices (e.g. 5 a-5 p) disclosedherein. Also, as shown in FIG. 54, tube 19 is in turn connected to aproximal handle, preferably comprising two mating portions 100 a, 100 b.Handle 100 a, 100 b is preferably made of a sterilizable, rigid, andnon-conductive material, such as a polymer (e.g. polycarbonate).

As with the other electrosurgical devices described within, a inputfluid line 4 b and a power source, preferably comprising generator 6preferably providing RF power via cable 9, are preferably fluidly andelectrically coupled, respectively, to the electrosurgical device 5 q.

With respect to the fluid coupling, fluid 24 from the fluid source 1 foruse with electrosurgical device 5 q preferably is communicated fromfluid source 1 through a flexible, polyvinylchloride (PVC) outlet fluidline 4 a to a flexible, polyvinylchloride (PVC) inlet fluid line 4 bconnected to the electrosurgical device 5 q. The outlet fluid line 4 andthe inlet fluid line are preferably connected via a male and femalemechanical fastener configuration, preferably comprising a Luer-Lok®connection from Becton, Dickinson and Company. The lumen of the inletline is then preferably interference fit over the outside diameter ofthe tube 19 to provide a press fit seal there between. Additionally anadhesive may be disposed there between to strengthen the seal. Fluid isthen communicated down the lumen 23 of the tube 19.

With respect to the electrical coupling, electrosurgical device 5 q ispreferably connected to the conductors 38 a, 38 b of insulatedelectrical wires 21 a, 21 b, respectively, which have been passedthrough lumen 23 of tube 19 after being spliced into the lumen of thepolyvinylchloride (PVC) inlet fluid line as branches from cable 9 whichis connected to generator 6.

As shown in FIG. 54, preferably the longitudinal axis 31 ofelectrosurgical device 5 q is preferably configured at an angle relativeto the longitudinal axis of tube 19. Preferably the longitudinal axis 31of electrosurgical device 5 q is configured at an angle of about 5degrees to 90 degrees relative to the longitudinal axis of tube 19. Morepreferably, the longitudinal axis 31 of electrosurgical device 5 q isconfigured at an angle of about 8 degrees to 45 degrees relative to thelongitudinal axis of tube 19.

In light of embodiments 5 a-5 q, the preferred electrosurgical device ofthe present invention may vary with application and use. For example,embodiments of devices with circumferentially directed fluid flowchannels (e.g. 5 n-5 p) are generally preferred over embodimentspredominately comprising longitudinally directed fluid flow channels(e.g. 5 a-5 m) when the longitudinal axis 31 of the devices are used ina substantially horizontal orientation. As shown in FIG. 55, device 5 pis being used in a substantially horizontal orientation with cylindricalportion 32 the device 5 p shown adjacent tissue 20 in a semi-circulartissue well 101, as shown encompassing about 180 degrees of theelectrosurgical device 5 p. However, in other embodiments, thesemi-circular tissue well 101 may encompass more or less than 180degrees of the electrosurgical device.

As shown in FIG. 55, a thin film of fluid 24 is provided fromelectrosurgical device 5 p and exists between electrosurgical device 5 pand tissue surface 102 near the bottom of well 101. However, tissue 20overlies and occludes the portion 55 a of the opening 55 of fluid flowchannel 54 located within the well 101 adjacent tissue 20, while thefluid flow channel 54 itself remains unoccluded. Consequently, whiletissue 20 inhibits fluid 24 from exiting fluid flow channel 54, it doesnot prevent fluid 24 in channel 54 from flowing within the confines ofthe channel 54. Thus, as the fluid flow channel 54 and opening 55 extendcircumferentially around electrosurgical device 5 p, with the portion 55b becoming unoccluded as the opening 55 emerges from well 100 and is nolonger adjacent tissue 20, fluid 24 may then exit the fluid flow channel54 at the tissue surface 102 adjacent the well 101.

Conversely, embodiments of devices with longitudinally directed fluidflow channels (e.g. 5 a-5 m) are generally preferred over embodimentspredominately comprising circumferentially directed fluid flow channels(e.g. 5 o) when the longitudinal axis 31 of the devices are used in asubstantially vertical orientation. As shown in FIG. 56, device 5 c isbeing used in a substantially vertical orientation with cylindricalportion 32 the device 5 c shown adjacent tissue 20 in circular tissuewell 102.

As shown in FIG. 56, tissue 20 overlies and occludes the portion 55 a ofthe opening 55 of fluid flow channel 54 located within the circular well103 adjacent tissue 20, while the fluid flow channel 54 itself remainsunoccluded. Consequently, while tissue 20 inhibits fluid from exitingfluid flow channel 54, it does not prevent fluid 24 in channel 54 fromflowing within the confines of the channel 54. Thus, as the fluid flowchannel 54 and opening 55 extend circumferentially aroundelectrosurgical device 5 c, with the portion 55 b becoming unoccluded asthe opening 55 emerges from well 103 and is no longer adjacent tissue20, fluid 24 may then exit the fluid flow channel 54 at the tissuesurface 104 adjacent the well 103.

Recognizing that the electrosurgical devices of the present inventionwill potentially be used in both horizontal orientations and verticalorientations, as well as any orientation in between, during their use,the electrosurgical devices of embodiments 5 n and 5 p may be preferableto certain of the other embodiments disclosed herein.

Another exemplary electrosurgical device of the present invention whichmay be used in conjunction with the system of the present invention isshown at reference character 5 r in FIG. 57, and more particularly inFIGS. 57-60. As best shown in FIG. 59, device 5 r is used in conjunctionwith instrument 64. As with certain other embodiments disclosed herein,instrument 64 is contained within the central flow passage 41 withinprobe body 26 and thereafter, with use, the instrument 64 is extendedfrom the distal end 27 of the electrosurgical device 5 r and probe body26 when the instrument 64 is extended distally. Also as disclosed withother embodiments, the instrument 64 (shown as a hollow needle with anopen, pointed tip) may be configured to penetrate tissue and enableinjection therapy to tissue, such as the administration of avasoconstrictor. sclerotic or topical anesthetic through the lumen of aneedle.

As shown in FIG. 59, central flow passage 41 comprises a lumen ofsubstantially uniform cross-sectional area and diameter along itslength. In addition to the above use for instrument 64 for device 5 r,it serves as an occlusion for occluding central flow passage 41 while aportion of instrument 64 is contained therein. Unlike previousembodiments, central flow passage 41 of device 5 r preferably does notprovide fluid 24 from lumen 23 of tube 19 to lateral flow passage 43 a,43 b. Rather, fluid 24 from lumen 23 of tube 19 is provided to lateralflow passages 43 a, 43 b through at least one off-center longitudinallydirected passage 104 parallel with the longitudinal axis 31 and centralflow passage 41. As shown, preferably passage 104 comprises a pluralityof passages 104 angularly uniformly distributed about the longitudinalaxis 31 and central flow passage 41.

With use of device 5 r, fluid 24 provided from lumen 23 of tube 19enters longitudinal flow passage fluid entrance opening 105 after thefluid flow is substantially inhibited from entering and flowing throughcentral flow passage 41 due to the presence of instrument 64.

In certain medical procedures, it may be necessary to irrigate a tissuetreatment site with a large volume of fluid either before, during orafter tissue treatment with the electrosurgical device 5 r. When suchirrigation is required, instrument 64 may be retracted proximally fromcentral flow passage 41, thus leaving central flow passage unoccluded byinstrument 64. Consequently, in seeking the path of least resistance,fluid 24 from lumen 23 now predominately flows through central flowpassage 41 and may be used, for example, to clean a tissue treatmentsite.

Another exemplary electrosurgical device of the present invention whichmay be used in conjunction with the system of the present invention isshown at reference character 5 s in FIG. 61, and more particularly inFIGS. 61-65. As shown in FIGS. 63-65, central flow passage 41 andlateral flow passages 43 a, 43 b have been eliminated. Thus, rather thanfluid 24 from lumen 23 first flowing through central flow passage 41 andlateral flow passages 43 a, 43 b before reaching fluid flow channel 54,fluid 24 from lumen 23 of tube 19 flows directly into fluid flow channel54. In other words, as shown in FIGS. 63-65, fluid flow channel 54 is indirect fluid communication with lumen 23 of tube 19.

As with other embodiments disclosed herein, fluid flow channels 54 andthe electrodes 29 a, 30 a in recesses 53 are substantially coextensive.In other words, they substantially coincide or are equally extensive inlocation and boundaries on electrosurgical device 5 s. As shown, inorder to facilitate direct fluid communication of fluid flow channels 54with lumen 23 of tube 19, preferably fluid flow channels 54 of device 5t are initiated within the confines of tube 19. In other words, withinthe lumen 23 of tube 19 proximal to distal end 18. As shown, for thisembodiment, because the fluid flow channels are initiated within theconfines of tube 19, preferably fluid flow channels 54 and electrodes 29a, 30 a, are initiated at remote locations. In other words, do notoverlie one another in the confines of tube 19. As shown, for aconfiguration of two electrodes and two flow channels, preferably theelectrical connection for the electrodes and the initiation of the flowchannels occurs approximately 90 degrees from one another onelectrosurgical device 5 s. In this manner, conductors 29/38 b and 30/38a are configured to remain electrically insulated from one another (andinhibit a short circuit from there between in the presence of anelectrically conductive fluid 24) by member 51 and the inner surface ofthe tube 19 which is preferably press fit against shoulder 34.

Preferably the relationship between the material for the probe body,electrodes and fluid throughout the various embodiments should be suchthat the fluid wets the surface of the probe body, plugs and/orelectrodes to form a continuous thin coating thereon and does not formisolated rivulets or beads. Contact angle, θ, is a quantitative measureof the wetting of a solid by a liquid. It is defined geometrically asthe angle formed by a liquid at the three phase boundary where a liquid,gas and solid intersect. In terms of the thermodynamics of the materialsinvolved, contact angle θ involves the interfacial free energies betweenthe three phases given by the equation γ_(1v) cos θ=γ_(sv)−γ_(s1) whereγ_(1v), γ_(sv) and γ_(s1) refer to the interfacial energies of theliquid/vapor, solid/vapor and solid/liquid interfaces, respectively. Ifthe contact angle θ is less than 90 degrees the liquid is said to wetthe solid. If the contact angle is greater than 90 degrees the liquid isnon-wetting. A zero contact angle represents complete wetting.

To effectively treat thick tissues, it can be advantageous to have theability to pulse the RF power on and off. Under some circumstances, thetemperature deep in tissue can rise quickly past the 100° C. desiccationpoint even though the electrode/tissue interface is boiling at 100° C.This manifests itself as “popping,” as steam generated deep in thetissue boils too fast and erupts toward the surface. In one embodimentof the invention, a switch is provided on the control device or customgenerator to allow the user to select a “pulse” mode of the RF power.Preferably, the RF power system in this embodiment is further controlledby software.

In some embodiments, it can be desirable to control the temperature ofthe conductive fluid before it is released from the electrosurgicaldevice. In one embodiment, a heat exchanger is provided for the outgoingsaline flow to either heat or chill the saline. The heat exchanger maybe provided as part of the electrosurgical device or as part of anotherpart of the system, such as within the enclosure 14. Pre-heating thesaline to a predetermined level below boiling reduces the transientwarm-up time of the device as RF is initially turned on, therebyreducing the time to cause coagulation of tissue. Alternatively,pre-chilling the saline is useful when the surgeon desires to protectcertain tissues at the electrode/tissue interface and treat only deepertissue. One exemplary application of this embodiment is the treatment ofvaricose veins, where it is desirable to avoid thermal damage to thesurface of the skin. At the same time, treatment is provided to shrinkunderlying blood vessels using thermal coagulation. The temperature ofthe conductive fluid prior to release from the surgical device cantherefore be controlled, to provide the desired treatment effect.

In another embodiment, the flow rate controller is modified to providefor a saline flow rate that results in greater than 100% boiling at thetissue treatment site. For example, the selection switch 12 of the flowrate controller 11 (shown in FIG. 1) can include settings thatcorrespond to 110%, 120% and greater percentages of boiling. Thesehigher settings can be of value to a surgeon in such situations as whenencountering thick tissue, wherein the thickness of the tissue canincrease conduction away from the electrode jaws. Since the basiccontrol strategy neglects heat conduction, setting for 100% boiling canresult in 80% of 90% boiling, depending upon the amount of conduction.Given the teachings herein, the switch of the flow rate controller canaccommodate any desirable flow rate settings, to achieve the desiredsaline boiling at the tissue treatment site.

The invention can, in some embodiments, deliver fast treatment of tissuewithout using a temperature sensor built into the device or a customspecial-purpose generator. In a preferred embodiment, there is nobuilt-in temperature sensor or other type of tissue sensor, nor is thereany custom generator. Preferably, the invention provides a means forcontrolling the flow rate to the device such that the device and flowrate controller can be used with a wide variety of general-purposegenerators. Any general-purpose generator is useable in connection withthe fluid delivery system and flow rate controller to provide thedesired power; the flow rate controller will accept the power andconstantly adjust the saline flow rate according to the controlstrategy. Preferably, the generator is not actively controlled by theinvention, so that standard generators are useable according to theinvention. Preferably, there is no active feedback from the device andthe control of the saline flow rate is “open loop.” Thus, in thisembodiment, the control of saline flow rate is not dependent onfeedback, but rather the measurement of the RF power going out to thedevice.

For purposes of the appended claims, the term “tissue” includes, but isnot limited to, organs (e.g. liver, lung, spleen, gallbladder), highlyvascular tissues (e.g. liver, spleen), soft and hard tissues (e.g.adipose, areolar, bone, bronchus-associated lymphoid, cancellous,chondroid, chordal, chromaffin, cicatricial, connective, elastic,embryonic, endothelial, epithelial, erectile, fatty, fibrous,gelatiginous, glandular, granulation, homologous, indifferent,interstitial, lymphadenoid, lymphoid, mesenchymal, mucosa-associatedlymphoid, mucous, muscular, myeloid, nerve, osseous, reticular, scar,sclerous, skeletal, splenic, subcutaneous), tissue masses (e.g. tumors),etc.

While a preferred embodiment of the present invention has beendescribed, it should be understood that various changes, adaptations andmodifications can be made therein without departing from the spirit ofthe invention and the scope of the appended claims. The scope of theinvention should, therefore, be determined not with reference to theabove description, but instead should be determined with reference tothe appended claims along with their full scope of equivalents.Furthermore, it should be understood that the appended claims do notnecessarily comprise the broadest scope of the invention which theApplicant is entitled to claim, or the only manner(s) in which theinvention may be claimed, or that all recited features are necessary.

All publications and patent documents cited in this application areincorporated by reference in their entirety for all purposes.

1. A medical device comprising: a catheter tube having a distal end anda lumen, the tube configured to assist in applying tamponage to ableeding source in a gastrointestinal tract when flexed; a catheter tipassembled with the tube adjacent the distal end of the tube, thecatheter tip having a catheter tip outer surface and including: a probebody comprising an electrically insulative material; at least oneelectrode pair, the electrode pair comprising a first electrode spacedfrom a second electrode, the first electrode and the second electrodelocated on the probe body; a fluid distribution manifold to direct afluid from inside the probe body towards the tip outer surface, themanifold comprises a central passage within the probe body and aplurality of lateral passages which extend from the central passagetowards the tip outer surface, the central passage narrowed at a distalend thereof; and an injection needle housed within the central passage,the needle extendable from the central passage to provide treatment totissue.
 2. The medical device of claim 1 wherein a portion of thecatheter tip is configured to be penetrated by a portion of the needle.3. The medical device of claim 1 wherein a portion of the catheter tipis configured to open around a portion of the needle.
 4. The medicaldevice of claim 1 wherein a portion of the catheter tip is configured toleast partially seal with a portion of the needle.
 5. The medical deviceof claim 1 wherein a portion of the catheter tip is configured toelectrically insulate the needle from the electrodes.
 6. The medicaldevice of claim 1 wherein a portion of the catheter tip provides a guideportion for guiding the needle from the lumen of the catheter tube tothe central passage within the probe body.
 7. The medical device ofclaim 1 wherein: the central passage extends to a central passage outletopening; and a portion of the needle occludes at least a portion of thecentral passage outlet opening.
 8. The medical device of claim 1 furthercomprising: a first electrical connection to the catheter tip; a secondelectrical connection to the catheter tip; and a member comprising anelectrically insulative portion, the electrically insulative portionelectrically insulating the first electrical connection from the secondelectrical connection to inhibit a short circuit from forming betweenthe two connections in the presence of an electrically conductive fluid.9. The medical device of claim 1 wherein: each electrode extendslongitudinally along the probe body; and the plurality of lateralpassages are spaced longitudinally along the probe body.
 10. The medicaldevice of claim 9 wherein: at least a portion of the plurality oflateral passages extend to an outlet opening located on the tip outersurface; and the tip outer surface comprises an outer surface of atleast one of the first and second electrodes.
 11. The medical device ofclaim 1 wherein: each electrode extends spirally around the probe body;and the plurality of lateral passages are spaced spirally around theprobe body.
 12. The medical device of claim 11 wherein: at least aportion of the plurality of lateral passages extend to an outlet openinglocated on the tip outer surface; and the tip outer surface comprises anouter surface of at least one of the first and second electrodes. 13.The medical device of claim 1 wherein: each electrode extends circularlyaround the probe body; and the plurality of lateral passages are spacedcircularly around the probe body.
 14. The medical device of claim 13wherein: at least a portion of the plurality of lateral passages extendto an outlet opening located on the tip outer surface; and the tip outersurface comprises an outer surface of at least one of the first andsecond electrodes.
 15. The medical device of claim 1 wherein: eachelectrode extends circumferentially around the probe body; and theplurality of lateral passages are spaced circumferentially around theprobe body.
 16. The medical device of claim 15 wherein: at least aportion of the plurality of lateral passages extend to an outlet openinglocated on the tip outer surface; and the tip outer surface comprises anouter surface of at least one of the first and second electrodes. 17.The medical device of claim 1 wherein: each electrode extends bothlongitudinally and circumferentially around the probe body; and theplurality of lateral passages are spaced both longitudinally andcircumferentially around the probe body.
 18. The medical device of claim17 wherein: at least a portion of the plurality of lateral passagesextend to an outlet opening located on the tip outer surface; and thetip outer surface comprises an outer surface of at least one of thefirst and second electrodes.
 19. The medical device of claim 1 whereinthe at least one electrode pair comprises two electrode pairs.
 20. Themedical device of claim 1 wherein the at least one electrode paircomprises three electrode pairs.